configs/microchip_sama5d2_icp_mmc_defconfig: drop BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_GIT=y

This defconfig is download at91bootstrap3 using a tarball, not over
git.

Fixes:

  configs/microchip_sama5d2_icp_mmc_defconfig:20:warning: override: BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_TARBALL changes choice state

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

configs/microchip_sama5d2_icp_mmc_defconfig

@@ -16,7 +16,6 @@ BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_4=y
 BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
 BR2_TARGET_AT91BOOTSTRAP3=y
-BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_GIT=y
 BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_TARBALL=y
 BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_TARBALL_LOCATION="$(call github,linux4sam,at91bootstrap,v4.0.0-rc2)/at91bootstrap-v4.0.0-rc2.tar.gz"
 BR2_TARGET_AT91BOOTSTRAP3_DEFCONFIG="sama5d2_icpsd_uboot"