mmc: sdhci_am654: Fix module autoload

Add a MODULE_DEVICE_TABLE() entry so that the driver is autoloaded
when built as a module.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Link: https://lore.kernel.org/r/20201008100129.13917-1-faiz_abbas@ti.com


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