selftests/powerpc: Fix spelling mistake "mmaping" -> "mmapping"

There is a spelling mistake in a perror message. Fix it.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221021084545.65973-1-colin.i.king@gmail.com

tools/testing/selftests/powerpc/ptrace/core-pkey.c

@@ -329,7 +329,7 @@ static int parent(struct shared_info *info, pid_t pid)
 
 	core = mmap(NULL, core_size, PROT_READ, MAP_PRIVATE, fd, 0);
 	if (core == (void *) -1) {
-		perror("Error mmaping core file");
+		perror("Error mmapping core file");
 		ret = TEST_FAIL;
 		goto out;
 	}