mac80211: enable CONFIG_BRCMFMAC_SDIO for imx/cortexa7

TechNexion PICO-PI-IMX7D uses BCM4339 Wi-Fi interface in SDIO mode.
Enable SDIO support for imx/cortexa7 to fully support it in images.

Signed-off-by: Lech Perczak <lech.perczak@gmail.com>

package/kernel/mac80211/broadcom.mk

@@ -450,6 +450,7 @@ define KernelPackage/brcmfmac/config
 	config BRCMFMAC_SDIO
 		bool "Enable SDIO bus interface support"
 		default y if TARGET_bcm27xx
+		default y if TARGET_imx_cortexa7
 		default y if TARGET_sunxi
 		default n
 		help