ARM: dts: dra76-evm: shift to using common IOdelay data

Now that we have a device-tree include file with common
MMC/SD IOdelay data for DRA76x SoC, shift the EVM device-tree
file to using that.
Also fix the name of the IO voltage regulator for mmc1.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>