ARM: mx6: ddr: Add support for iMX6UL/ULL/SL/SDL

ARM: mx6: ddr: Add support for iMX6UL/ULL/SL/SDL

This patch adds support for iMX6UL/ULL/SL/SDL MMDC into the DDR calibration
code. The difference between MX6DQ and MX6UL/ULL/SL is that the later SoCs
have 2 SDQS registers, just like MX6SX, while the MX6DQ/MX6SDL has 8.

Fixes: 4f4c128c65 ("ARM: mx6: ddr: Add support for iMX6SX")
Signed-off-by: Marek Vasut <[email protected]>
Cc: Eric Nelson <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Stefano Babic <[email protected]>
Reviewed-by: Fabio Estevam <[email protected]>