configs/at91sam9g20dfc: remove defconfig, broken

This defconfig no longer builds:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/11012272524

It is still based on the 4.8.6 kernel, which is not even an LTS
kernel, so we cannot easily update to fix the issues which are most
likely due to the newer gcc/binutils versions we're using now.

There is no DEVELOPERS entry attached to this configuration as well,
and this defconfig has been broken for at least 2 months, probably
more (our Gitlab CI history is only kept for ~2 months). So let's drop
it, unless someone volunteers to resurrect it.

Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Patrice Vilchez <Patrice.Vilchez@microchip.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>

.checkpackageignore

@@ -107,7 +107,6 @@ configs/aspeed_ast2600evb_defconfig lib_defconfig.ForceCheckHash
 configs/asus_tinker-s_rk3288_defconfig lib_defconfig.ForceCheckHash
 configs/asus_tinker_rk3288_defconfig lib_defconfig.ForceCheckHash
 configs/at91sam9260eknf_defconfig lib_defconfig.ForceCheckHash
-configs/at91sam9g20dfc_defconfig lib_defconfig.ForceCheckHash
 configs/at91sam9g45m10ek_defconfig lib_defconfig.ForceCheckHash
 configs/at91sam9rlek_defconfig lib_defconfig.ForceCheckHash
 configs/atmel_sama5d27_som1_ek_mmc_dev_defconfig lib_defconfig.ForceCheckHash

configs/at91sam9g20dfc_defconfig

@@ -1,21 +0,0 @@
-BR2_arm=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_8=y
-BR2_LINUX_KERNEL=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.8.6"
-BR2_LINUX_KERNEL_DEFCONFIG="at91_dt"
-BR2_LINUX_KERNEL_DTS_SUPPORT=y
-BR2_LINUX_KERNEL_INTREE_DTS_NAME="at91sam9g20ek"
-BR2_TARGET_ROOTFS_UBI=y
-BR2_TARGET_ROOTFS_UBIFS_MAXLEBCNT=2047
-BR2_TARGET_AT91BOOTSTRAP3=y
-BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_GIT=y
-BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_REPO_URL="https://github.com/linux4sam/at91bootstrap.git"
-BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_REPO_VERSION="v3.10.3"
-BR2_TARGET_AT91BOOTSTRAP3_DEFCONFIG="at91sam9g20eknf_uboot"
-BR2_TARGET_UBOOT=y
-BR2_TARGET_UBOOT_BUILD_SYSTEM_KCONFIG=y
-BR2_TARGET_UBOOT_CUSTOM_VERSION=y
-BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2016.09.01"
-BR2_TARGET_UBOOT_BOARD_DEFCONFIG="at91sam9g20ek_nandflash"
-BR2_PACKAGE_HOST_SAM_BA=y