ARM: edma: Add DT and runtime PM support to the private EDMA API

Adds support for parsing the TI EDMA DT data into the required EDMA
private API platform data. Enables runtime PM support to initialize
the EDMA hwmod. Enables build on OMAP.

Changes by Joel:
* Setup default one-to-one mapping for queue_priority and queue_tc
mapping as discussed in [1].
* Split out xbar stuff to separate patch. [1]
* Dropped unused DT helper to convert to array
* Fixed dangling pointer issue with Sekhar's changes

[1] https://patchwork.kernel.org/patch/2226761/

Signed-off-by: Matt Porter <mporter@ti.com>
[nsekhar@ti.com: fix checkpatch errors, build breakages. Introduce
edma_setup_info_from_dt() as part of that effort]
Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>