This adds support for new board variants. Now Supported are:

- i.MX6q module with 1GiB Micron RAM
- i.MX6d/q modules with 1GiB/2GiB Nanya RAM
- i.MX6s modules with 512MiB/1GiB Nanya RAM

This has been tested on:

- i.MX6q module with 1GiB Micron RAM
- i.MX6d module with 2GiB Nanya RAM
- i.MX6s module with 1GiB Nanya RAM

The possible RAM equipment is:

- For the 512MiB module: 2x Nanya nt5cb128m16fp-di
- For the 1GiB modules: 2x Nanya nt5cc256m16cp or 4x Micron MT41K128M16JT-125
- For the 2GiB module: 4x Nanya nt5cc256m16cp

The 512MiB Nanya board is assumed to work with the same DCD table
as the 1GiB Nanya board. The variant is detected by mirroring at
512MiB, but this hasn't been tested by Pengutronix.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>