mb/google/skyrim: Create morthal variant

Create the morthal variant of the skyrim reference board by copying
the template files to a new directory named for the variant.

(Auto-Generated by create_coreboot_variant.sh version 4.5.0).

BUG=b:240970782
BRANCH=None
TEST=util/abuild/abuild -p none -t google/skyrim -x -a
make sure the build includes GOOGLE_MORTHAL

Signed-off-by: Moises <moisesgarcia@google.com>
Change-Id: I25c25f067a040e6930f4fc60fadb8be85dc8eda6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66989
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Jon Murphy <jpmurphy@google.com>

src/mainboard/google/skyrim/Kconfig

@@ -66,6 +66,7 @@ config MAINBOARD_FAMILY
 config MAINBOARD_PART_NUMBER
 	default "Skyrim" if BOARD_GOOGLE_SKYRIM
 	default "Winterhold" if BOARD_GOOGLE_WINTERHOLD
+	default "Morthal" if BOARD_GOOGLE_MORTHAL
 
 config OVERRIDE_DEVICETREE
 	string
@@ -75,6 +76,7 @@ config VARIANT_DIR
 	string
 	default "skyrim" if BOARD_GOOGLE_SKYRIM
 	default "winterhold" if BOARD_GOOGLE_WINTERHOLD
+	default "morthal" if BOARD_GOOGLE_MORTHAL
 
 config VBOOT
 	select VBOOT_LID_SWITCH