mtd: msm_qpic_nand: fix bit flipped data in erased pages

Some filesystems like UBIFS might expect the data read from an erased
page be all 0xff. In case there is a bit flip in the device then the
data in that page would not all be 0xff's.

While the page would have been identified as an erased page and there
wont be an other errors generated, the data still needs to be fixed,
which is beind done here.

Change-Id: Idd30a2bf50f5782691973df804711fb1c0719f6a
Signed-off-by: Krishna Konda <kkonda@codeaurora.org>