net: fill in MODULE_DESCRIPTION()s for SLIP

W=1 builds now warn if module is built without a MODULE_DESCRIPTION().
Add descriptions to the Serial Line (SLIP) protocol modules.
Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20240108181610.2697017-3-leitao@debian.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/slip/slhc.c

@@ -752,4 +752,5 @@ EXPORT_SYMBOL(slhc_compress);
 EXPORT_SYMBOL(slhc_uncompress);
 EXPORT_SYMBOL(slhc_toss);
 
+MODULE_DESCRIPTION("Compression helpers for SLIP (serial line)");
 MODULE_LICENSE("Dual BSD/GPL");

drivers/net/slip/slip.c

@@ -1437,5 +1437,6 @@ static void sl_keepalive(struct timer_list *t)
 }
 
 #endif
+MODULE_DESCRIPTION("SLIP (serial line) protocol module");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_LDISC(N_SLIP);