MLK-13361-2 arm: imx6q: busfreq: wrap ralat settings on a macro

MLK-13361-2 arm: imx6q: busfreq: wrap ralat settings on a macro

Setting the Read Additional Latency (RALAT) to 2 cycles,
MMDCx_MDMISC[RALAT] = 2, is needed for 24MHz operation point.

Currently this is set within the "set_timings_below_100MHz_operation"
macro, which is use for the 24MHz case.

In order to provide a generic way for setting RALAT=2 the code
is wrapped in this new macro: "set_mmdc_misc_ralat_2_cycles", so
other set points (besides the below 100MHz case) can reuse this code.

As an example, for 100Mhz operation the RALAT should be set to 2 cycles,
however, the rest of the MMDCFG parameter are not the same as in the
"below_100MHz" case. So, this macro can be reused for its RALAT part.

Signed-off-by: Juan Gutierrez <juan.gutierrez@nxp.com>