Sync all am57xx based dts files with latest Linux

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

As per mmc device tree binding documentation card detect gpio has
to be active low signal. When a hardware is designed with active
high card detect, gpio polarity has to be changed with
cd-inverted dt property.

In DRA72x and AM57xx EVMs the card detect gpio is designed as
active low gpio. So correcting the dt card detect gpio
definition.

Also adding card-detect gpio for DRA74x EVM.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

Import various DT files for am57xx-beagle-x15 from
Linux Kernel v4.2
Add config file for this board, enable DM, DM_GPIO,
DM_SERIAL and DM_MMC.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>