s390: rename CALL_ON_STACK_NORETURN() to call_on_stack_noreturn()

Lower case matches the call_on_stack() macro and is easier to read.

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