mmc: zynq_sdhci: Added qurik to disable high speed

mmc: zynq_sdhci: Added qurik to disable high speed

Add quirk to disable high speed incase the high
speed was broken.This solves the issue where the
the controller is used in High Speed Mode and the
the hold time requirement for the JEDEC/MMC 4.41
specification is NOT met.
This timing issue is not on all boards and hence
provided config option to enable it when required.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Emil Lenchak <emill@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>