mfd: Constify regmap and irq configuration data

Constify in various drivers configuration data which is not modified:
 - regmap_irq_chip,
 - individual regmap_irq's in array,
 - regmap_config,
 - irq_domain_ops,

Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/intel_soc_pmic_core.h b/drivers/mfd/intel_soc_pmic_core.h
index 9498d67..ff2464b 100644
--- a/drivers/mfd/intel_soc_pmic_core.h
+++ b/drivers/mfd/intel_soc_pmic_core.h
@@ -24,7 +24,7 @@
 	struct mfd_cell *cell_dev;
 	int n_cell_devs;
 	const struct regmap_config *regmap_config;
-	struct regmap_irq_chip *irq_chip;
+	const struct regmap_irq_chip *irq_chip;
 };
 
 extern struct intel_soc_pmic_config intel_soc_pmic_config_crc;