ARM: dts: AM57xx: EVM/X15: MMC: Add higher speed mode support

Latest boards for AM57xx BeagleBoard-X15 and AM57xx-EVM (Rev A3a)
have vdd_3v3 connected to vdd and ldo1 connected to MMC1 IO lines.
This allows AM57xx BeagleBoard-X15 and AM57xx-EVM to support
UHS modes since ldo1 regulator can provide 1.8v.

Modify MMC1 dt node to reflect the regulator change. Add
the UHS capabilities to MMC1 dt node and also add IODelay values
corresponding to the UHS modes. These IODelay values are for
SR2.0 of AM572x since newer boards have SR2.0 silicon.

Also added IODelay values for MMC2 DDR mode corresponding to
SR2.0 silicon.

IOdelay data is based on SPRS953, revised December 2015.

Link: http://www.ti.com/lit/ds/symlink/am5728.pdf



Tested-by: Yan Liu <yan-liu@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>