iommu/omap: Drop redundant check if ti,syscon-mmuconfig exists

iommu/omap: Drop redundant check if ti,syscon-mmuconfig exists

The syscon_regmap_lookup_by_phandle() will fail if property does not
exist, so doing of_property_read_bool() earlier is redundant.  Drop that
check and move error message to syscon_regmap_lookup_by_phandle() error
case while converting it to dev_err_probe().

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20250624-syscon-phandle-args-iommu-v3-1-1a36487d69b8@linaro.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>