bcm53xx: drop downstream patch for Buffalo WZR-1750DHP button

This patch never received a proper description and was never sent
upstream as supposed. It was meant to be handled in 2015-2018 so it
should be safe to assume noone really understands it or care.

Cc: Felix Fietkau <[email protected]>
Signed-off-by: Rafał Miłecki <[email protected]>

target/linux/bcm53xx/patches-5.10/311-ARM-BCM5301X-Add-power-button-for-Buffalo-WZR-1750DHP.patch

@@ -1,20 +0,0 @@
-From: Felix Fietkau <[email protected]>
-Subject: [PATCH] ARM: BCM5301X: Add power button for Buffalo WZR-1750DHP
-
-Signed-off-by: Felix Fietkau <[email protected]>
----
---- a/arch/arm/boot/dts/bcm4708-buffalo-wzr-1750dhp.dts
-+++ b/arch/arm/boot/dts/bcm4708-buffalo-wzr-1750dhp.dts
-@@ -100,6 +100,12 @@
- 	gpio-keys {
- 		compatible = "gpio-keys";
- 
-+		power {
-+			label = "Power";
-+			linux,code = <KEY_POWER>;
-+			gpios = <&chipcommon 1 GPIO_ACTIVE_LOW>;
-+		};
-+
- 		restart {
- 			label = "Reset";
- 			linux,code = <KEY_RESTART>;