signal/powerpc: Remove redefinition of NSIGTRAP on powerpc

NSIGTRAP is 4 in the generic siginfo and powerpc just undefines
NSGTRAP and redefine it as 4.  That accomplishes nothing so remove
the duplication.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

arch/powerpc/include/uapi/asm/siginfo.h

@@ -15,9 +15,6 @@
 
 #include <asm-generic/siginfo.h>
 
-#undef NSIGTRAP
-#define NSIGTRAP	4
-
 /*
  * SIGFPE si_codes
  */