mb/google/zork: Select VBOOT by default

Zork boards will not boot without PSP verstage/VBOOT, so select it
by default.

Change-Id: I2447bf69baefd5560a0153dcd3d9b87b0a91a3f9
Signed-off-by: Matt DeVillier <matt.devillier@amd.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69763
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/zork/Kconfig

@@ -107,6 +107,9 @@ config VGA_BIOS
 	default y if USE_AMD_BLOBS
 
 config VBOOT
+	bool
+	# selected by default as PSP verstage required for booting at present time
+	default y
 	select EC_GOOGLE_CHROMEEC_SWITCHES
 	select VBOOT_LID_SWITCH
 	select VBOOT_STARTS_BEFORE_BOOTBLOCK