util/mainboard/google: Fix hatch variant script

The script had a couple of bugs:
 * It didn't create the required directory under variants/
 * It was treating the wildcard as literal and so couldn't
   find variant files to copy.

V.2: Drop verbose cp && fixup wild card usage.

Change-Id: Ie6f4179014b79ea45d0fcf406ca192046438dbf7
Signed-off-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35553
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Andrew McRae <amcrae@chromium.org>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>

util/mainboard/google/hatch/create_coreboot_variant.sh

@@ -53,7 +53,8 @@ DATE=$(date +%Y%m%d)
 git checkout -b "create_${variant}_${DATE}"
 
 # Copy the template tree to the target
-cp -r "${SRC}/template/*" "variants/${variant}/"
+mkdir -p "variants/${variant}/"
+cp -pr "${SRC}/template/." "variants/${variant}/"
 git add "variants/${variant}/"
 
 # Now add the new variant to Kconfig and Kconfig.name