remoteproc: st: Use syscon_regmap_lookup_by_phandle_args

Use syscon_regmap_lookup_by_phandle_args() which is a wrapper over
syscon_regmap_lookup_by_phandle() and getting the argument.  Except
simpler code this annotates within one line that given phandle has
arguments, so grepping for code would be easier.

There is also no real benefit in printing errors on missing syscon
argument, because this is done just too late: runtime check on
static/build-time data.  Dtschema and Devicetree bindings offer the
static/build-time check for this already.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Link: https://lore.kernel.org/r/20250111-b4-syscon-phandle-args-remoteproc-v1-5-73ed6fafa1e3@linaro.org


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>