jbd2: add missing MODULE_DESCRIPTION()

Fix the 'make W=1' warning:
WARNING: modpost: missing MODULE_DESCRIPTION() in fs/jbd2/jbd2.o
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://patch.msgid.link/20240526-md-fs-jbd2-v1-1-7bba6665327d@quicinc.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/jbd2/journal.c

@@ -3157,6 +3157,7 @@ static void __exit journal_exit(void)
 	jbd2_journal_destroy_caches();
 }
 
+MODULE_DESCRIPTION("Generic filesystem journal-writing module");
 MODULE_LICENSE("GPL");
 module_init(journal_init);
 module_exit(journal_exit);