selftests/powerpc/pmu: fix spelling mistake "mis-match" -> "mismatch"

There are a few spelling mistakes in error messages. Fix them.
Signed-off-by: NColin Ian King <colin.i.king@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220319232025.22067-1-colin.i.king@gmail.com

tools/testing/selftests/powerpc/security/spectre_v2.c

@@ -198,7 +198,7 @@ int spectre_v2_test(void)
 				return 4;
 			}
 			printf("Branch misses > 15%% unexpected in this configuration!\n");
-			printf("Possible mis-match between reported & actual mitigation\n");
+			printf("Possible mismatch between reported & actual mitigation\n");
 
 			return 1;
 		}
@@ -207,14 +207,14 @@ int spectre_v2_test(void)
 		// This seems to affect userspace branch prediction a bit?
 		if (miss_percent > 25) {
 			printf("Branch misses > 25%% unexpected in this configuration!\n");
-			printf("Possible mis-match between reported & actual mitigation\n");
+			printf("Possible mismatch between reported & actual mitigation\n");
 			return 1;
 		}
 		break;
 	case COUNT_CACHE_DISABLED:
 		if (miss_percent < 95) {
 			printf("Branch misses < 95%% unexpected in this configuration!\n");
-			printf("Possible mis-match between reported & actual mitigation\n");
+			printf("Possible mismatch between reported & actual mitigation\n");
 			return 1;
 		}
 		break;