mmc: arasan: Fix the issue in reading tap values from DT

mmc: arasan: Fix the issue in reading tap values from DT

'of_property_read_variable_u32_array' function returns number
of elements read on success. This patch updates the condition
check in the driver to overwrite the tap values from DT if exist.

Signed-off-by: Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@xilinx.com>
Signed-off-by: Manish Narani <manish.narani@xilinx.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/1623753837-21035-8-git-send-email-manish.narani@xilinx.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>