powerpc: Wire up sys_userfaultfd()

The selftest passes on 64-bit LE and BE.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/systbl.h

@@ -368,3 +368,4 @@ SYSCALL_SPU(memfd_create)
 SYSCALL_SPU(bpf)
 COMPAT_SYS(execveat)
 PPC64ONLY(switch_endian)
+SYSCALL_SPU(userfaultfd)

arch/powerpc/include/asm/unistd.h

@@ -12,7 +12,7 @@
 #include <uapi/asm/unistd.h>
 
 
-#define __NR_syscalls		364
+#define __NR_syscalls		365
 
 #define __NR__exit __NR_exit
 #define NR_syscalls	__NR_syscalls

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

@@ -386,5 +386,6 @@
 #define __NR_bpf		361
 #define __NR_execveat		362
 #define __NR_switch_endian	363
+#define __NR_userfaultfd	364
 
 #endif /* _UAPI_ASM_POWERPC_UNISTD_H_ */