regulator: act8945a-regulator: Implement PM functionalities

The regulator supports a dedicated suspend mode.
Implement the appropriate ->set_suspend_xx() hooks, add support for
->set_mode(), and provide basic PM ops functionalities to setup the
regulator in a suspend state when the system is entering suspend.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
[claudiu.beznea@microchip.com: remove shutdown function, use dev_pm_ops,
 fix checkpatch warning, adapt commit message, add LDO modes support,
 move modes constants to active-semi,8945a-regulator.h, remove rdevs from
 struct act8945a_pmic, add op_mode to act8945a_pmic]
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/dt-bindings/regulator/active-semi,8945a-regulator.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2018 Microchip Technology, Inc. All rights reserved.
+ *
+ * Device Tree binding constants for the ACT8945A PMIC regulators
+ */
+
+#ifndef _DT_BINDINGS_REGULATOR_ACT8945A_H
+#define _DT_BINDINGS_REGULATOR_ACT8945A_H
+
+/*
+ * These constants should be used to specify regulator modes in device tree for
+ * ACT8945A regulators as follows:
+ * ACT8945A_REGULATOR_MODE_FIXED:	It is specific to DCDC regulators and it
+ *					specifies the usage of fixed-frequency
+ *					PWM.
+ *
+ * ACT8945A_REGULATOR_MODE_NORMAL:	It is specific to LDO regulators and it
+ *					specifies the usage of normal mode.
+ *
+ * ACT8945A_REGULATOR_MODE_LOWPOWER:	For DCDC and LDO regulators; it specify
+ *					the usage of proprietary power-saving
+ *					mode.
+ */
+
+#define ACT8945A_REGULATOR_MODE_FIXED		1
+#define ACT8945A_REGULATOR_MODE_NORMAL		2
+#define ACT8945A_REGULATOR_MODE_LOWPOWER	3
+
+#endif