s390/ipl,decrompressor: disable branch profiling

The early kernel decrompressing code can't call into the kernel
in order to profile branches. Fixes this link error:

arch/s390/boot/compressed/misc.o: In function `decompress_kernel':
misc.c:(.text+0x9a6): undefined reference to `ftrace_likely_update'

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>