Remove patch since potentially dangerous

A proper fix might be adoption of Icenowy's newer DT changes, see https://forum.armbian.com/topic/6650-toolchain-banana-pi-m2-zero-h3/?do=findComment&comment=50539

patch/u-boot/u-boot-sunxi/fix-sdcard-detect-bpi-m2z.patch

@@ -1,16 +0,0 @@
-diff -Naur v2017.09/drivers/mmc/sunxi_mmc.c v2017.09-bpi-m2z/drivers/mmc/sunxi_mmc.c
---- v2017.09/drivers/mmc/sunxi_mmc.c	2017-09-19 08:15:12.948794321 +0800
-+++ v2017.09-bpi-m2z/drivers/mmc/sunxi_mmc.c	2017-11-08 09:21:20.000000000 +0800
-@@ -465,7 +465,12 @@
- 	if (cd_pin < 0)
- 		return 1;
- 
-+#ifdef BPI
- 	return !gpio_get_value(cd_pin);
-+#else
-+	printf("BPI: skip sunxi_mmc_getcd pin %d(%d)\n",cd_pin, gpio_get_value(cd_pin));
-+	return 1;
-+#endif
- }
- 
- static const struct mmc_ops sunxi_mmc_ops = {