xtensa: don't reimplement force_sigsegv()

Instead of open coding the sequence from force_sigsegv() just call it.
This also fixes a bug because we were modifying ka->sa.sa_handler (which
is a copy of sighand->action[]), whereas the intention of the code was to
modify sighand->action[] directly.

As the original code was working with a copy it had no effect on signal
delivery.

Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/xtensa/kernel/signal.c

@@ -425,9 +425,7 @@ static void setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	return;
 
 give_sigsegv:
-	if (sig == SIGSEGV)
-		ka->sa.sa_handler = SIG_DFL;
-	force_sig(SIGSEGV, current);
+	force_sigsegv(sig, current);
 }
 
 /*