linux-phytec-ti

remoteproc/pru: use macros and types from omap mailbox

The actual payload size for OMAP Mailboxes is 32-bits, and the type
to use with the OMAP Mailbox driver is mbox_msg_t. This type can vary
in size (32-bits or 64-bits) depending on the platform the driver is
being built for. Update the PRU remoteproc driver to use the types and
macros provided by the OMAP Mailbox driver to always convert safely
between the mailbox payload size and the pointers the data is exchanged
between the OMAP Mailbox implementation driver and its client drivers.

Signed-off-by: Suman Anna <s-anna@ti.com>