s390: disable branch profiling for vdso

When branch profiling is enabled, if () gets annotated with code to
instrument the hit/miss ratio. This doesn't work for VDSO as we can't
access kernel code. Add -DDISABLE_BRANCH_PROFILING to fix this.

Reported-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>