mmc: sdhci_am654: Fix hard coded otap delay array size

Change hard coded array size value to depend on struct timing_data
array size.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Link: https://lore.kernel.org/r/20200923105206.7988-4-faiz_abbas@ti.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>