buildroot

beaglebone: defconfigs: select ext4 as rootfs

Select ext4 as root file system as the genimage config expects ext4 not ext2.
Tested on beaglebone, beagleboneblack and AM335x EVM

[Peter: reworded slightly]
Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>