mb/google/poppy: Introduce VARIANT_SPECIFIC_OPTIONS_*

In order to allow variants to select different Kconfig options, this
change adds VARIANT_SPECIFIC_OPTIONS_${VARIANT_NAME} which can be
selected by each variant in Kcnonfig.name.

Change-Id: I15db2fdac5c9e55f9698c8a0c083d6467afae245
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/22700
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/mainboard/google/poppy/Kconfig.name b/src/mainboard/google/poppy/Kconfig.name
index ec4342b..e012928 100644
--- a/src/mainboard/google/poppy/Kconfig.name
+++ b/src/mainboard/google/poppy/Kconfig.name
@@ -1,11 +1,14 @@
 config BOARD_GOOGLE_POPPY
 	bool "Poppy"
 	select BOARD_GOOGLE_BASEBOARD_POPPY
+	select VARIANT_SPECIFIC_OPTIONS_POPPY
 
 config BOARD_GOOGLE_NAUTILUS
 	bool "Nautilus"
 	select BOARD_GOOGLE_BASEBOARD_POPPY
+	select VARIANT_SPECIFIC_OPTIONS_NAUTILUS
 
 config BOARD_GOOGLE_SORAKA
 	bool "Soraka"
 	select BOARD_GOOGLE_BASEBOARD_POPPY
+	select VARIANT_SPECIFIC_OPTIONS_SORAKA