config/raspberrypi: remove non-DT defconfig

The RPi is slowly but surely dropping support for booting without a DTB,
so just ditch our old defconfig now that we have up-to-date DT-enabled
defconfigs for all RPi models (save for the compute module).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Floris Bos <bos@je-eigen-domein.nl>
Cc: Pascal de Bruijn <pmjdebruijn@pcode.nl>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

configs/raspberrypi_defconfig

@@ -1,21 +0,0 @@
-BR2_arm=y
-BR2_arm1176jzf_s=y
-
-BR2_TOOLCHAIN_BUILDROOT_CXX=y
-
-BR2_TARGET_GENERIC_GETTY_PORT="tty1"
-
-BR2_PACKAGE_RPI_FIRMWARE=y
-
-# Lock to 3.12 headers as the RPi kernel is based off the 3.12 branch
-BR2_KERNEL_HEADERS_VERSION=y
-BR2_DEFAULT_KERNEL_VERSION="3.12.28"
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_12=y
-
-BR2_LINUX_KERNEL=y
-BR2_LINUX_KERNEL_CUSTOM_GIT=y
-BR2_LINUX_KERNEL_CUSTOM_REPO_URL="git://github.com/raspberrypi/linux.git"
-BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="c256eb9968c8997dce47350d2075e42f1b3991d3"
-BR2_LINUX_KERNEL_USE_DEFCONFIG=y
-BR2_LINUX_KERNEL_DEFCONFIG="bcmrpi_quick"
-BR2_LINUX_KERNEL_ZIMAGE=y