parisc: Drop struct sigaction from not exported header file

This header file isn't exported to userspace, so there is no benefit in
defining struct sigaction for userspace here.

Signed-off-by: Helge Deller <[e-mail]>

arch/parisc/include/asm/signal.h

···
 	unsigned long sig[_NSIG_WORDS];
 } sigset_t;
 
-#ifndef __KERNEL__
-struct sigaction {
-	__sighandler_t sa_handler;
-	unsigned long sa_flags;
-	sigset_t sa_mask;		/* mask last for extensibility */
-};
-#endif
-
 #include <asm/sigcontext.h>
 
 #endif /* !__ASSEMBLY */