kmsan: test: add module description

Every module should have a description, and kbuild now warns for those
that don't.

WARNING: modpost: missing MODULE_DESCRIPTION() in mm/kmsan/kmsan_test.o

Link: https://lkml.kernel.org/r/20250603075323.1839608-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Macro Elver <elver@google.com>
Cc: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: arndb

mm/kmsan/kmsan_test.c

@@ -732,3 +732,4 @@ kunit_test_suites(&kmsan_test_suite);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Alexander Potapenko <glider@google.com>");
+MODULE_DESCRIPTION("Test cases for KMSAN");