sparc: fix warning in userspace header traps.h

Fix following warning:
traps.h:23: extern's make no sense in userspace

Add an ifdef __KERNEL__ block that cover the
extern definition and a few related things that neither
is for userspace.

Signed-off-by: Sam Ravnborg <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

arch/sparc/include/asm/traps.h

···
 #define NUM_SPARC_TRAPS  255
 
 #ifndef __ASSEMBLY__
-
+#ifdef __KERNEL__
 /* This is for V8 compliant Sparc CPUS */
 struct tt_entry {
 	unsigned long inst_one;
···
 	__asm__ __volatile__("rd %%tbr, %0\n\t" : "=r" (tbr));
 	return tbr;
 }
-
+#endif /* (__KERNEL__) */
 #endif /* !(__ASSEMBLY__) */
 
 /* For patching the trap table at boot time, we need to know how to