Kconfig: comply to Linux 5.3's Kconfig language rules

Kconfig became stricter on what it accepts, so accomodate before
updating to a new release.

Change-Id: I92a9e9bf0d557a7532ba533cd7776c48f2488f91
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37156
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/src/cpu/intel/Kconfig b/src/cpu/intel/Kconfig
index c21de59..43b360b 100644
--- a/src/cpu/intel/Kconfig
+++ b/src/cpu/intel/Kconfig
@@ -1,31 +1,31 @@
 # CPU models
-source src/cpu/intel/model_6xx/Kconfig
-source src/cpu/intel/model_65x/Kconfig
-source src/cpu/intel/model_67x/Kconfig
-source src/cpu/intel/model_68x/Kconfig
-source src/cpu/intel/model_6bx/Kconfig
-source src/cpu/intel/model_6ex/Kconfig
-source src/cpu/intel/model_6fx/Kconfig
-source src/cpu/intel/model_1067x/Kconfig
-source src/cpu/intel/model_106cx/Kconfig
-source src/cpu/intel/model_206ax/Kconfig
-source src/cpu/intel/model_2065x/Kconfig
-source src/cpu/intel/model_f2x/Kconfig
-source src/cpu/intel/model_f3x/Kconfig
-source src/cpu/intel/model_f4x/Kconfig
-source src/cpu/intel/haswell/Kconfig
+source "src/cpu/intel/model_6xx/Kconfig"
+source "src/cpu/intel/model_65x/Kconfig"
+source "src/cpu/intel/model_67x/Kconfig"
+source "src/cpu/intel/model_68x/Kconfig"
+source "src/cpu/intel/model_6bx/Kconfig"
+source "src/cpu/intel/model_6ex/Kconfig"
+source "src/cpu/intel/model_6fx/Kconfig"
+source "src/cpu/intel/model_1067x/Kconfig"
+source "src/cpu/intel/model_106cx/Kconfig"
+source "src/cpu/intel/model_206ax/Kconfig"
+source "src/cpu/intel/model_2065x/Kconfig"
+source "src/cpu/intel/model_f2x/Kconfig"
+source "src/cpu/intel/model_f3x/Kconfig"
+source "src/cpu/intel/model_f4x/Kconfig"
+source "src/cpu/intel/haswell/Kconfig"
 # Sockets/Slots
-source src/cpu/intel/slot_1/Kconfig
-source src/cpu/intel/socket_BGA956/Kconfig
-source src/cpu/intel/socket_FCBGA559/Kconfig
-source src/cpu/intel/socket_m/Kconfig
-source src/cpu/intel/socket_p/Kconfig
-source src/cpu/intel/socket_mPGA604/Kconfig
-source src/cpu/intel/socket_441/Kconfig
-source src/cpu/intel/socket_LGA775/Kconfig
+source "src/cpu/intel/slot_1/Kconfig"
+source "src/cpu/intel/socket_BGA956/Kconfig"
+source "src/cpu/intel/socket_FCBGA559/Kconfig"
+source "src/cpu/intel/socket_m/Kconfig"
+source "src/cpu/intel/socket_p/Kconfig"
+source "src/cpu/intel/socket_mPGA604/Kconfig"
+source "src/cpu/intel/socket_441/Kconfig"
+source "src/cpu/intel/socket_LGA775/Kconfig"
 # Architecture specific features
-source src/cpu/intel/fit/Kconfig
-source src/cpu/intel/turbo/Kconfig
-source src/cpu/intel/common/Kconfig
-source src/cpu/intel/microcode/Kconfig
-source src/cpu/intel/car/non-evict/Kconfig
+source "src/cpu/intel/fit/Kconfig"
+source "src/cpu/intel/turbo/Kconfig"
+source "src/cpu/intel/common/Kconfig"
+source "src/cpu/intel/microcode/Kconfig"
+source "src/cpu/intel/car/non-evict/Kconfig"