configs/microchip_sam9x60ek_mmc_dev_defconfig: add quotes around string

Commit 616ba9c90b014637dc9925fa442a0af4a11f04b8 extended rootfs size, but
forgot to add quotes around it. Thus, kconfig removed the option
entirely.

While we're at it, move the option to a more appropriate place together
with the rest of the ext2 options.

Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/2103784289

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

@@ -7,7 +7,6 @@ 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="$(call github,linux4microchip,linux,linux4microchip-2021.10)/linux-linux4microchip-2021.10.tar.gz"
@@ -67,6 +66,7 @@ BR2_PACKAGE_HTOP=y
 BR2_PACKAGE_VIM=y
 BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_4=y
+BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
 BR2_TARGET_AT91BOOTSTRAP3=y
 BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_TARBALL=y
 BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_TARBALL_LOCATION="$(call github,linux4sam,at91bootstrap,v4.0.1)/at91bootstrap-v4.0.1.tar.gz"