MLK-10576 ARM: i.MX6: exclude the ARM errata from i.MX6 UP system

The ARM errata 751472, 794072, 761320, 845369 only applied
to the following configuration:

This erratum affects configurations with either:
- One processor if the ACP is present
- Two or more processors

i.MX6 family does not have the ACP and thus only the MPCore system
will be impacted, which are the i.MX6DQ, i.MX6DL.

Signed-off-by: Nitin Garg <nitin.garg@freescale.com>
Signed-off-by: Jason Liu <r64343@freescale.com>
(cherry picked from commit 0db960784ba4f631ee5c0321b5d25f3b1ac55640)