linux-phytec-ti

soc: ti: pruss: Parse various syscon nodes and store their regmaps

The PRUSS device node currently uses three different syscon nodes for
CFG, IEP and MII_RT sub-modules. Parse these syscon nodes and store
their regmap handles to allow adding functions to program any register
within these sub-modules.

The MFD_SYSCON Kconfig option is also enabled whenever the PRUSS remoteproc
driver is enabled. The MFD_SYSCON is a boolean option, and the select
dependency option is chosen following the majority usage style within the
kernel, as well as to align with similar usage in couple of other
remoteproc drivers.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>