mac80211: brcm: fix compilation warning for unused brcmf_of_fwnames

If CPTCFG_BRCMFMAC_SDIO is not used brcmf_of_fwnames is defined but not
used in the case of CONFIG_OF not compiled.

Restrict brcmf_of_fwnames only with CPTCFG_BRCMFMAC_SDIO selected.
Fix compilation warning:
/__w/openwrt/openwrt/openwrt/build_dir/target-x86_64-openwrt-linux-musl_musl/linux-x86_64/backports-6.1.24/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.h:16:1: error: 'brcmf_of_fwnames' defined but not used [-Werror=unused-function]
   16 | brcmf_of_fwnames(struct device *dev, u32 *map_count)
      | ^~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Signed-off-by: Christian Marangi <[email protected]>

package/kernel/mac80211/patches/brcm/865-brcmfmac-Read-alternative-firmware-names-from-DT.patch

@@ -65,22 +65,26 @@ Signed-off-by: Phil Elwell <[email protected]>
 +}
 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.h
 +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.h
-@@ -5,9 +5,16 @@
+@@ -5,9 +5,20 @@
  #ifdef CONFIG_OF
  void brcmf_of_probe(struct device *dev, enum brcmf_bus_type bus_type,
  		    struct brcmf_mp_device *settings);
++#ifdef CPTCFG_BRCMFMAC_SDIO
 +struct brcmf_firmware_mapping *
 +brcmf_of_fwnames(struct device *dev, u32 *map_count);
++#endif
  #else
  static void brcmf_of_probe(struct device *dev, enum brcmf_bus_type bus_type,
  			   struct brcmf_mp_device *settings)
  {
  }
++#ifdef CPTCFG_BRCMFMAC_SDIO
 +static struct brcmf_firmware_mapping *
 +brcmf_of_fwnames(struct device *dev, u32 *map_count)
 +{
 +	return NULL;
 +}
++#endif
  #endif /* CONFIG_OF */
 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
 +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c