build: Fix checking result of sizeof instead of memcmp

This can be easily spot when building with clang:

emulator/smp.c:373:53: error: size argument in 'memcmp' call is a comparison
      [-Werror,-Wmemsize-comparison]
        if (memcmp(conn->pcnf, confirm, sizeof(conn->pcnf) != 0)) {

tools/smp-tester.c:596:53: error: size argument in 'memcmp' call is a comparison
      [-Werror,-Wmemsize-comparison]
        if (memcmp(data->pcnf, confirm, sizeof(data->pcnf) != 0)) {
diff --git a/emulator/smp.c b/emulator/smp.c
index 40836cf..c30de36 100644
--- a/emulator/smp.c
+++ b/emulator/smp.c
@@ -370,7 +370,7 @@
 				conn->ra_type, conn->ra, confirm))
 		return false;
 
-	if (memcmp(conn->pcnf, confirm, sizeof(conn->pcnf) != 0)) {
+	if (memcmp(conn->pcnf, confirm, sizeof(conn->pcnf)) != 0) {
 		printf("Confirmation values don't match\n");
 		return false;
 	}
diff --git a/tools/smp-tester.c b/tools/smp-tester.c
index d24c9b2..90b091e 100644
--- a/tools/smp-tester.c
+++ b/tools/smp-tester.c
@@ -593,7 +593,7 @@
 					data->ra_type, data->ra, confirm))
 		return false;
 
-	if (memcmp(data->pcnf, confirm, sizeof(data->pcnf) != 0)) {
+	if (memcmp(data->pcnf, confirm, sizeof(data->pcnf)) != 0) {
 		tester_warn("Confirmation values don't match");
 		return false;
 	}