ARM: tsimx6ul: Disable CFG80211 default powersave

[reapplies commit 494e41b]

Testing found that powersave modes negatively impact WILC3000
modules and BLE/Wi-Fi coexistance that was introduced in recent
wilc driver updates. Disabling powersave by default addresses
a lot of these issues.

arch/arm/configs/tsimx6ul_defconfig

@@ -390,6 +390,7 @@ CONFIG_BT_MRVL=m
 CONFIG_BT_ATH3K=m
 CONFIG_CFG80211=y
 CONFIG_NL80211_TESTMODE=y
+# CONFIG_CFG80211_DEFAULT_PS is not set
 CONFIG_CFG80211_WEXT=y
 CONFIG_MAC80211=m
 CONFIG_MAC80211_MESH=y