[rfc] init: e2fsck /storage

call for testing...

fs breakage on RPi (and even x86*, yes that happens!) is something that we ignore for too long. we failed miserably here...

this is a blind c/p from my fork, not tested as I dont compile from OE git, so please TEST it first on top of current master.

pls note the comments in check_part() and let me know what you think.

ping @sraue and @MilhouseVH  I'd appreciate if you take a look

EDIT: use "dd if=/dev/zero of=/dev/mmcblk0p2 seek=8 bs=512 count=4" to simulate (non-fatal) fs breakage.