Introduce CONFIG_GOOGLE_FIRMWARE

In order to keep Google's firmware drivers organized amongst themselves,
all Google firmware drivers are gated on CONFIG_GOOGLE_FIRMWARE=y, which
defaults to 'n' in the kernel build.

Signed-off-by: Mike Waychison <mikew@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index d7d6009..47338c9 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -14,4 +14,4 @@
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
 obj-$(CONFIG_SIGMA)		+= sigma.o
 
-obj-y  += google/
+obj-$(CONFIG_GOOGLE_FIRMWARE)	+= google/