nit6xlite bootscript: add disable_giga flag

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
mmc: fsl_esdhc: fix f_max retrieval during init

for multi instance API we use struct fsl_esdhc_cfg to
pass the clock rate. Do not set f_max from global data,
since this is wrong for multi instance case.

Signed-off-by: Markus Niebel <Markus.Niebel@tq-group.com>