configs/microchip_sam9x60ek_mmc_dev_defconfig: expand rootfs size to 120M

Default 60M for rootfs are not enough and generate a build failure, so
let's expand rootfs size to 120M.

Fixes:
https://gitlab.com/ymorin/buildroot/-/jobs/2035821088

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

configs/microchip_sam9x60ek_mmc_dev_defconfig

@@ -7,6 +7,7 @@ BR2_TARGET_GENERIC_HOSTNAME="sam9x60ek"
 BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y
 BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
 BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/microchip/sam9x60ek_mmc/genimage.cfg"
+BR2_TARGET_ROOTFS_EXT2_SIZE=120M
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_TARBALL=y
 BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION="$(call github,linux4microchip,linux,linux4microchip-2021.10)/linux-linux4microchip-2021.10.tar.gz"