Trim EXTRAVERSION in the Makefile on CI builds
    
    The CI build currently adds the full git commit hash to the release of
    the RPM it builds. This breaks the kernel build as the EXTRAVERSION
    cannot exceed 64 characters.
    
    This sets the EXTRAVERSION to whatever the release was minus
    ".pr.<hash>".
    
    Signed-off-by: Jeremy Cline <jcline@redhat.com>