mx6: soc: update get_cpu_rev and get_imx_type for mx6solo/sololite

Previously, the same value was returned for both mx6dl and mx6solo.
Check number of processors to differeniate.
Also, a freescale patch says that sololite has its cpu/rev
stored at 0x280 instead of 0x260.
I don't have a sololite to verify.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>