board: ti: am57xx: enable input on mmc clock

board: ti: am57xx: enable input on mmc clock

As per the latest pinmux data available for AM572x EVM,
rev A3, input should be enabled on MMC clock lines for
MMC2/2/3 for stable operation.

Further, AM572x TRM, SPRUHZ6, Revised June 2016, in
section 18.4.6.1.1 "Pad Configuration Registers" states
that input should be enabled for MMC 2/3/4 clock lines.

Enable input on MMC1 and MMC3 clock to match the latest
pinmux data. Input is already enabled on MMC2 clock for
BeagleBoard x15. Further, input is already enabled on all
MMCx clocks for other AM57xx boards (AM572x and AM571x
IDK).

Tested with HS and UHS SD card on AM572x EVM Rev A3.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>