brcmfmac: make debug module parameter more clear

The module parameter definition for brcmf_msg_level has been
reworked to a named module parameter with description so
modinfo is a bit more informative:

parm:           debug:level of debug output (int)
Reviewed-by: NHante Meuleman <meuleman@broadcom.com>
Reviewed-by: NPiotr Haber <phaber@broadcom.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/brcm80211/brcmfmac/dhd_linux.c

@@ -40,7 +40,8 @@ MODULE_LICENSE("Dual BSD/GPL");
 
 /* Error bits */
 int brcmf_msg_level;
-module_param(brcmf_msg_level, int, 0);
+module_param_named(debug, brcmf_msg_level, int, S_IRUSR | S_IWUSR);
+MODULE_PARM_DESC(debug, "level of debug output");
 
 /* P2P0 enable */
 static int brcmf_p2p_enable;