s390: Initialize psw mask in perf_arch_fetch_caller_regs()

Also initialize regs->psw.mask in perf_arch_fetch_caller_regs().
This way user_mode(regs) will return false, like it should.

It looks like all current users initialize regs to zero, so that this
doesn't fix a bug currently. However it is better to not rely on callers
to do this.

Fixes: 914d52e4 ("s390: implement perf_arch_fetch_caller_regs")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/include/asm/perf_event.h

@@ -49,6 +49,7 @@ struct perf_sf_sde_regs {
 };
 
 #define perf_arch_fetch_caller_regs(regs, __ip) do {			\
+	(regs)->psw.mask = 0;						\
 	(regs)->psw.addr = (__ip);					\
 	(regs)->gprs[15] = (unsigned long)__builtin_frame_address(0) -	\
 		offsetof(struct stack_frame, back_chain);		\