mb/google/brya: Support power sequencing for USB-only WWAN

Nissa is using the FM101 which is USB only. To allow us to reuse the
existing wwan_power.asl for power sequencing, move the PCIe-specific
part behind a new Kconfig HAVE_PCIE_WWAN.

BUG=b:217092522
TEST=Build brya0 and check that generated dsdt.asl doesn't change.

Signed-off-by: Reka Norman <rekanorman@google.com>
Change-Id: Icb6db91ce00deb2b30379f5ff7a974d1feb62ea8
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61693
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kangheui Won <khwon@chromium.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
diff --git a/src/mainboard/google/brya/Kconfig b/src/mainboard/google/brya/Kconfig
index 86c546d..001332d 100644
--- a/src/mainboard/google/brya/Kconfig
+++ b/src/mainboard/google/brya/Kconfig
@@ -205,7 +205,11 @@
 	  Select this if the variant has a WWAN module and requires the poweroff sequence
 	  to be performed on shutdown. Must define WWAN_FCPO, WWAN_RST and WWAN_PERST GPIOs
 	  in variant.h, as well as T1_OFF_MS (time between PERST & RST) and T2_OFF_MS (time
-	  between RST and FCPO).
+	  between RST and FCPO). WWAN_PERST and T1_OFF_MS are only necessary for PCIe WWAN
+	  (when HAVE_PCIE_WWAN is also selected).
+
+config HAVE_PCIE_WWAN
+	def_bool n
 
 config USE_PM_ACPI_TIMER
 	default n