s390/cpum_sf: Ignore qsi() return code

qsi() executes the instruction qsi (query sample information)
and stores the result of the query in a sample information block
pointed to by the function argument. The instruction does not
change the condition code register. The return code is always
zero. No need to check for errors. Remove now unreferenced
macros PMC_FAILURE and RS_INIT_FAILURE_QSI.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>