SUNRPC: Properly terminate test case arrays

Unable to handle kernel paging request at virtual address 73657420 when execute
[73657420] *pgd=00000000
Internal error: Oops: 80000005 [#1] ARM
CPU: 0 PID: 1 Comm: swapper Tainted: G                 N 6.2.0-rc7-00133-g373f26a81164-dirty #9
Hardware name: Generic DT based system
PC is at 0x73657420
LR is at kunit_run_tests+0x3e0/0x5f4

On x86 with GCC 12, the missing array terminators did not seem to
matter. Other platforms appear to be more picky.
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/auth_gss/gss_krb5_test.c

@@ -519,6 +519,7 @@ static struct kunit_case rfc3961_test_cases[] = {
 		.run_case		= kdf_case,
 		.generate_params	= rfc3961_kdf_gen_params,
 	},
+	{}
 };
 
 static struct kunit_suite rfc3961_suite = {
@@ -780,6 +781,7 @@ static struct kunit_case rfc3962_test_cases[] = {
 		.run_case		= rfc3962_encrypt_case,
 		.generate_params	= rfc3962_encrypt_gen_params,
 	},
+	{}
 };
 
 static struct kunit_suite rfc3962_suite = {
@@ -1415,6 +1417,7 @@ static struct kunit_case rfc6803_test_cases[] = {
 		.run_case		= rfc6803_encrypt_case,
 		.generate_params	= rfc6803_encrypt_gen_params,
 	},
+	{}
 };
 
 static struct kunit_suite rfc6803_suite = {
@@ -1907,6 +1910,7 @@ static struct kunit_case rfc8009_test_cases[] = {
 		.run_case		= rfc8009_encrypt_case,
 		.generate_params	= rfc8009_encrypt_gen_params,
 	},
+	{}
 };
 
 static struct kunit_suite rfc8009_suite = {
@@ -2029,6 +2033,7 @@ static struct kunit_case encryption_test_cases[] = {
 		.run_case		= encrypt_selftest_case,
 		.generate_params	= encrypt_selftest_gen_params,
 	},
+	{}
 };
 
 static struct kunit_suite encryption_test_suite = {