fat: Remove redundant code
fat: Remove redundant code

We read from block device, and just after that fill buffer with
zeroes. That doesn't make much sense.

Kakadu/embox,mike2390/embox,embox/embox,mike2390/embox,mike2390/embox,Kakadu/embox,mike2390/embox,embox/embox,mike2390/embox,embox/embox,Kakadu/embox,embox/embox,mike2390/embox,Kakadu/embox,Kakadu/embox,embox/embox,embox/embox,Kakadu/embox,mike2390/embox,Kakadu/embox