remoteproc: pru: Add support for various PRU cores on K3 J721E SoCs

remoteproc: pru: Add support for various PRU cores on K3 J721E SoCs

The K3 J721E family of SoCs have a revised version of the AM65x ICSSG IP
and contains two instances of this newer ICSSG IP. Each ICSSG processor
subsystem contains 2 primary PRU cores, 2 auxiliary PRU cores called RTUs,
and 2 new auxiliary cores called Transmit PRUs (Tx_PRUs).

Enhance the existing PRU remoteproc driver to support these new PRU
and RTU cores by using specific compatibles. The cores have the same
memory copying limitations as on AM65x, so reuses the custom memcpy
function within the driver's ELF loader implementation. The initial
names for the firmware images for each PRU core are retrieved from
DT nodes, and can be adjusted through sysfs if required.

Signed-off-by: Suman Anna <s-anna@ti.com>
Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20201208141002.17777-7-grzegorz.jaszczyk@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>