configs/orangepi_plus: remove defconfig

This defconfig has been failing to build for several months, with
nobody stepping up to fix it. It's time to drop it.

See
https://lore.kernel.org/buildroot/20220806224338.0159e15c@windsurf/
for a notification on August 6, 2022 about the issues with this
defconfig.

This defconfig did not even have an entry in the DEVELOPERS file.

Fixes:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/3234499140

Cc: Shyam Saini <shyam.saini@amarulasolutions.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

board/orangepi/orangepi-plus/boot.cmd

@@ -1,8 +0,0 @@
-setenv fdt_high ffffffff
-
-setenv bootargs console=ttyS0,115200 earlyprintk root=/dev/mmcblk0p2 rootwait
-
-fatload mmc 0 $kernel_addr_r zImage
-fatload mmc 0 $fdt_addr_r sun8i-h3-orangepi-plus.dtb
-
-bootz $kernel_addr_r - $fdt_addr_r

board/orangepi/orangepi-plus/genimage.cfg

@@ -1,36 +0,0 @@
-# Minimal SD card image for the OrangePi Plus\Plus2
-#
-image boot.vfat {
-	vfat {
-		files = {
-			"zImage",
-			"sun8i-h3-orangepi-plus.dtb",
-			"boot.scr"
-		}
-	}
-
-	size = 10M
-}
-
-image sdcard.img {
-	hdimage {
-	}
-
-	partition u-boot {
-		in-partition-table = "no"
-		image = "u-boot-sunxi-with-spl.bin"
-		offset = 8K
-		size = 1016K # 1MB - 8KB
-	}
-
-	partition boot {
-		partition-type = 0xC
-		bootable = "true"
-		image = "boot.vfat"
-	}
-
-	partition rootfs {
-		partition-type = 0x83
-		image = "rootfs.ext4"
-	}
-}

board/orangepi/orangepi-plus/readme.txt

@@ -1,29 +0,0 @@
-OrangePi Plus/Plus2
-
-Intro
-=====
-
-This default configuration will allow you to start experimenting with the
-buildroot environment for the OrangePi Plus/Plus2. With the current configuration
-it will bring-up the board, and allow access through the serial console.
-
-How to build it
-===============
-
-Configure Buildroot:
-
-    $ make orangepi_plus_defconfig
-
-Compile everything and build the SD card image:
-
-    $ make
-
-How to write the SD card
-========================
-
-Once the build process is finished you will have an image called "sdcard.img"
-in the output/images/ directory.
-
-Copy the bootable "sdcard.img" onto an SD card with "dd":
-
-  $ sudo dd if=output/images/sdcard.img of=/dev/sdX