at91sam9x5ek_mmc_dev_defconfig: increase ext2 filesystem size

at91sam9x5ek_mmc_dev_defconfig: increase ext2 filesystem size

Since commit c6bca8cef0 removed autocalculation of the ext2 filesystem
size, the default size is now set to 60MB. However, this is just too
small for at91sam9x5ek_mmc_dev_defconfig, which has a lot of extra
packages for development.

Increase the filesystem size to 120000K, which is a nice and round
number and leaves enough space for overhead on a 128MB flash drive.
Only 65MB is used.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>