mtd: rawnand: pl353: Allow raw read/write only for on-die ecc flash parts

mtd: rawnand: pl353: Allow raw read/write only for on-die ecc flash parts

When using HW-ECC, do not assign pl353_read_page_raw() and
pl353_write_page_raw() to ecc->write_page_raw and ecc->read_page_raw
hooks. if we do that read and writes will fail. We came to know this,
when running mtd_nandbiterrs test. This test case uses raw read/writes
when assigned but with hw-ecc, causes failures in data read
and writes.

Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>