ARM: dts: am43x-epos-evm: add SD card hotplug support

Add card detect gpio for SD card slot and include dt gpio header.

Signed-off-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>