imx: Check the PL310 version for applying errata

imx: Check the PL310 version for applying errata

Apply errata based on PL310 version instead of compile
time. Also set Prefetch offset to 15, since it improves
memcpy performance by 35%. Don't enable Incr double
Linefill enable since it adversely affects memcpy
performance by about 32MB/s and reads by 90MB/s. Tested
with 4K to 16MB sized src and dst aligned buffer.

Signed-off-by: Nitin Garg <nitin.garg@freescale.com>
Signed-off-by: Ye Li <ye.li@nxp.com>