MLK-10496: detect 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.

Conflicts:
	arch/arm/mach-imx/system.c

Signed-off-by: Nitin Garg <nitin.garg@freescale.com>
(cherry picked from commit 8b44de98)