util/crossgcc: use fixed length version string.

After merging util/crossgcc: derive date and version from latest commit
(https://review.coreboot.org/c/coreboot/+/30804),
crossgcc build is broken in internal repository due to long version
name;coreboot.org repository is ok because it uses short tag name.
The patch uses "git describe" which is dependent on git tag name.
If tag name is little bit long, it can cause crossgcc build failed.

To avoid this issue, use only short version of hash string
which is fixed length. And it's enough as version string,
because we also use date(CROSSGCC_DATE) together.

TEST=Build crossgcc in both coreboot.org and internal repository
which uses longer tag name and check version string in build log.

Change-Id: I405b2e4e5c05831c25aebf1c73a281adab8ef452
Signed-off-by: Wonkyu Kim <wonkyu.kim@intel.com>
Reviewed-on: https://review.coreboot.org/c/31001
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/crossgcc/buildgcc

@@ -31,7 +31,7 @@
 cd "$(dirname "$0")" || exit 1
 
 CROSSGCC_DATE="$(git log -n 1 --pretty=%ad --date=short .)"
-CROSSGCC_VERSION="$(git describe $(git log -n 1 --pretty=%h .))"
+CROSSGCC_VERSION="$(git log -n 1 --pretty=%h .)"
 CROSSGCC_COMMIT=$( git describe )
 
 # default settings