OvmfPkg/create-release.py: Support git hash versions

OvmfPkg/create-release.py: Support git hash versions

Previously we would run 'git svn info' if a .svn directory
wasn't found. This would fail if the current local commit
was not from git-svn.

Now we look for the svn info in the output from git log.
If the svn version is not in a git-svn-id tag from
git log, then we use the git commit hash.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15042 6f19259b-4bc3-4df7-8a09-765794883524