beagleplay: Add DFU support

beagleplay: Add DFU support

DFU mode on a beagleplay can be used via the Type-C connector by holding
the USR switch while powering on.

Configuration is already provided as fragments for both the A53 and R5
u-boot parts. Include the am62x_a53_usbdfu.config config. The
am62x_r5_usbdfu.config fragment needs to be added should DFU boot be
required as this will disable booting from persistent storage due to
binary size constraints.

Signed-off-by: Sjoerd Simons <[email protected]>
Signed-off-by: Martyn Welch <[email protected]>
Reviewed-by: Mattijs Korpershoek <[email protected]>
Tested-by: Mattijs Korpershoek <[email protected]>