ipq40xx: add PoE passthrough GPIO

Add the GPIO pin of the PoE passthrough switch on the Aruba AP-303H.
Power is activated when the pin is low. It enables a PSE chip, so power
is only supplied to downstream devices when they are 802.3af/at
compliant devices.

Ensure you use a sufficient power supply when chaining a consuming
device after the AP.

Signed-off-by: David Bauer <[email protected]>
(cherry picked from commit b40cc46)

target/linux/ipq40xx/base-files/etc/board.d/03_gpio_switches

@@ -6,6 +6,9 @@ board_config_update
 board=$(board_name)
 
 case "$board" in
+aruba,ap-303h)
+	ucidef_add_gpio_switch "poe_passtrough" "POE passtrough disable" "546" "1"
+	;;
 cellc,rtl30vw)
 	ucidef_add_gpio_switch "w_disable" "W_DISABLE mPCIE pin" "398" "1"
 	ucidef_add_gpio_switch "pmd_resin_n" "PMD_RESIN_N pin" "399" "1"