MLK-13361-3 arm: imx6q: busfreq: restore mmdc timing settings for 100MHz

MLK-13361-3 arm: imx6q: busfreq: restore mmdc timing settings for 100MHz

The timing settings for 100MHz are almost the same as the ones for
400MHz except for the MMDCx_MISC[RALAT] parameter which needs to be
set to 2 cycles.

For the 100MHz case the restoration of the mmdc setting should be performed
in 2 steps: restore the mmdc setting and then overwrite the RALAT setting
for 2 cycles.

A decision code within the "mmdc_clk_lower_equal_100MHz" macro is added
to go to the "equal to 100MHz" or to the "lower to 100MHz" case

Signed-off-by: Juan Gutierrez <juan.gutierrez@nxp.com>
Signed-off-by: Alejandro Lozano <alejandro.lozano@nxp.com>