imx: add i.MX 6SLL CPU type

Add i.MX6SLL cpu type.
MXC_CPU_MX6D is not a real value in chip, so change it to 0x6A.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
3 files changed