Turn off mwifiex.

When enabled on the quantenna v37.4.2.89 kernel, system
crashes shortly after booting.

Change-Id: I16421638d35b0bfd39bbff9b985a56d809187618
diff --git a/arch/arc/configs/gfrg240_defconfig b/arch/arc/configs/gfrg240_defconfig
index 1ec4df9..ce56b8b 100644
--- a/arch/arc/configs/gfrg240_defconfig
+++ b/arch/arc/configs/gfrg240_defconfig
@@ -172,8 +172,6 @@
 # CONFIG_WLAN_VENDOR_CISCO is not set
 # CONFIG_WLAN_VENDOR_INTEL is not set
 # CONFIG_WLAN_VENDOR_INTERSIL is not set
-CONFIG_MWIFIEX=m
-CONFIG_MWIFIEX_PCIE=m
 # CONFIG_WLAN_VENDOR_MEDIATEK is not set
 # CONFIG_WLAN_VENDOR_RALINK is not set
 # CONFIG_WLAN_VENDOR_REALTEK is not set