brcmfmac: detect firmware support for monitor interface

Many/most of firmwares support creating monitor interface but only the
most recent ones explicitly /announce/ it using a "monitor" entry in the
list of capabilities.

Check for that entry and store internally info about monitor mode
support using a new feature flag. Once we sort out all details of
handling monitor interface it will be used when reporting available
interfaces to the cfg80211.

Later some fallback detecion method may be added for older firmwares.
For now just stick to the "monitor" capability which should be 100%
reliable.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/feature.c

@@ -48,6 +48,7 @@ static const struct brcmf_feat_fwcap brcmf_fwcap_map[] = {
 	{ BRCMF_FEAT_MBSS, "mbss" },
 	{ BRCMF_FEAT_MCHAN, "mchan" },
 	{ BRCMF_FEAT_P2P, "p2p" },
+	{ BRCMF_FEAT_MONITOR, "monitor" },
 };
 
 #ifdef DEBUG

drivers/net/wireless/broadcom/brcm80211/brcmfmac/feature.h

@@ -33,6 +33,7 @@
  * MFP: 802.11w Management Frame Protection.
  * GSCAN: enhanced scan offload feature.
  * FWSUP: Firmware supplicant.
+ * MONITOR: firmware can pass monitor packets to host.
  */
 #define BRCMF_FEAT_LIST \
 	BRCMF_FEAT_DEF(MBSS) \
@@ -48,7 +49,8 @@
 	BRCMF_FEAT_DEF(WOWL_ARP_ND) \
 	BRCMF_FEAT_DEF(MFP) \
 	BRCMF_FEAT_DEF(GSCAN) \
-	BRCMF_FEAT_DEF(FWSUP)
+	BRCMF_FEAT_DEF(FWSUP) \
+	BRCMF_FEAT_DEF(MONITOR)
 
 /*
  * Quirks: