kunit: add missing MODULE_DESCRIPTION() macros to lib/*.c

make allmodconfig && make W=1 C=1 reports for lib/*kunit:
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/bitfield_kunit.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/checksum_kunit.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/cmdline_kunit.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/is_signed_type_kunit.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/overflow_kunit.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/stackinit_kunit.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.

Link: https://lkml.kernel.org/r/20240601-md-lib-kunit-tests-v1-1-4493fe0032b9@quicinc.com
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/bitfield_kunit.c

@@ -151,4 +151,5 @@ static struct kunit_suite bitfields_test_suite = {
 kunit_test_suites(&bitfields_test_suite);
 
 MODULE_AUTHOR("Johannes Berg <johannes@sipsolutions.net>");
+MODULE_DESCRIPTION("Test cases for bitfield helpers");
 MODULE_LICENSE("GPL");

lib/checksum_kunit.c

@@ -639,4 +639,5 @@ static struct kunit_suite checksum_test_suite = {
 kunit_test_suites(&checksum_test_suite);
 
 MODULE_AUTHOR("Noah Goldstein <goldstein.w.n@gmail.com>");
+MODULE_DESCRIPTION("Test cases csum_* APIs");
 MODULE_LICENSE("GPL");

lib/cmdline_kunit.c

@@ -153,4 +153,5 @@ static struct kunit_suite cmdline_test_suite = {
 };
 kunit_test_suite(cmdline_test_suite);
 
+MODULE_DESCRIPTION("Test cases for API provided by cmdline.c");
 MODULE_LICENSE("GPL");

lib/is_signed_type_kunit.c

@@ -46,4 +46,5 @@ static struct kunit_suite is_signed_type_test_suite = {
 
 kunit_test_suite(is_signed_type_test_suite);
 
+MODULE_DESCRIPTION("is_signed_type() KUnit test suite");
 MODULE_LICENSE("Dual MIT/GPL");

lib/overflow_kunit.c

@@ -1237,4 +1237,5 @@ static struct kunit_suite overflow_test_suite = {
 
 kunit_test_suite(overflow_test_suite);
 
+MODULE_DESCRIPTION("Test cases for arithmetic overflow checks");
 MODULE_LICENSE("Dual MIT/GPL");

lib/stackinit_kunit.c

@@ -471,4 +471,5 @@ static struct kunit_suite stackinit_test_suite = {
 
 kunit_test_suites(&stackinit_test_suite);
 
+MODULE_DESCRIPTION("Test cases for compiler-based stack variable zeroing");
 MODULE_LICENSE("GPL");