mm/zsmalloc: add MODULE_DESCRIPTION()

Fix the 'make W=1' warning:

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

Link: https://lkml.kernel.org/r/20240513-mm-md-v1-4-8c20e7d26842@quicinc.comSigned-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/zsmalloc.c

@@ -2276,3 +2276,4 @@ module_exit(zs_exit);
 
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
+MODULE_DESCRIPTION("zsmalloc memory allocator");