s390: Rename GCC_ASM_FLAG_OUTPUT_BROKEN to CC_ASM_FLAG_OUTPUT_BROKEN

Config options which can be used to check for compiler bugs and features
have the compiler independent CC prefix in order to avoid duplicating and
having to check config options for multiple compilers. Therefore rename the
config option accordingly.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>