soc: ti: pruss: Add pruss_cfg_read()/update(), pruss_cfg_get_gpmux()/set_gpmux() APIs

Add two new generic API pruss_cfg_read() and pruss_cfg_update() to
the PRUSS platform driver to read and program respectively a register
within the PRUSS CFG sub-module represented by a syscon driver. These
APIs are internal to PRUSS driver.

Add two new helper functions pruss_cfg_get_gpmux() & pruss_cfg_set_gpmux()
to get and set the GP MUX mode for programming the PRUSS internal wrapper
mux functionality as needed by usecases.

Various useful registers and macros for certain register bit-fields and
their values have also been added.

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>
Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Link: https://lore.kernel.org/r/20230414045542.3249939-4-danishanwar@ti.com


Signed-off-by: Nishanth Menon <nm@ti.com>