apm821xx: WNDR4700: fix fan-control

This service was unfunctional due to not having its executable bit set.
Furthermore, sysupgrade complains about the file being present in images.

Also, the tc654 driver doesn't provide pwm1_enable sysfs file, instead its
now called pwm1_mode.

Please note that the fan was always spinning. It should now turn off, when
there's enough the thermal headroom.

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

target/linux/apm821xx/base-files/etc/init.d/hwmon_fancontrol

@@ -9,7 +9,7 @@ boot() {
 	case $(board_name) in
 	netgear,wndr4700)
 		path_to_hwmon='/sys/devices/platform/plb/plb:opb/4ef600700.i2c/i2c-0/0-001b/hwmon/hwmon1'
-		echo 1 > "$path_to_hwmon/pwm1_enable"
+		echo 1 > "$path_to_hwmon/pwm1_mode"
 		;;
 	esac
 }