linux-phytec-ti

ARM: dts: AM33xx: Replace mailboxes with PRU system events

The virtio/rpmsg communication between MPU and a PRU core is currently
achieved using the OMAP mailbox IP that provides the inter-processor
interrupt signalling. Switch these mailboxes to use the PRU system
events so that the interrupt signalling can be achieved through a
mechanism internal to the PRUSS itself, and eliminating an external
peripheral access from the PRU-side. The difference from MPU would
be minimal in using one versus the other.

This switch is done for all AM33xx boards. Mailboxes can still be
used if desired. Either approach would require that an appropriate
firmware image is loaded/booted on the PRU.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>