ar71xx: enable ethernet LED of Arduino Yun

Commit 05d73a2a73 enabled GPIO on ethernet LED, but proper LED setup was
not added then. This commit fixes it by reverting the change on the LED.

Fixes: 05d73a2a73 ("ar71xx: Arduino Yun board 'WLAN RST' button support")
Signed-off-by: Sungbo Eo <mans0n@gorani.run>
(cherry picked from commit a5e404d1923d135d335e4ece83f87e6e891396e2)

target/linux/ar71xx/files/arch/mips/ath79/mach-arduino-yun.c

@@ -117,8 +117,7 @@ static void __init ds_setup(void)
 	ath79_gpio_function_disable(AR933X_GPIO_FUNC_ETH_SWITCH_LED0_EN |
 								AR933X_GPIO_FUNC_ETH_SWITCH_LED1_EN |
 								AR933X_GPIO_FUNC_ETH_SWITCH_LED2_EN |
-								AR933X_GPIO_FUNC_ETH_SWITCH_LED3_EN |
-								AR933X_GPIO_FUNC_ETH_SWITCH_LED4_EN);
+								AR933X_GPIO_FUNC_ETH_SWITCH_LED3_EN);
 
 	//Disable the Function for some pins to have GPIO functionality active
 	// GPIO6-7-8 and GPIO11