regulator: Introduce property to flag set-load support

Introduce "regulator-allow-set-load" property to make it possible to
flag in the board configuration that a regulator is allowed to have the
load requirements changed.

Signed-off-by: Bjorn Andersson <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/regulator.txt

···
 - regulator-always-on: boolean, regulator should never be disabled
 - regulator-boot-on: bootloader/firmware enabled regulator
 - regulator-allow-bypass: allow the regulator to go into bypass mode
+- regulator-allow-set-load: allow the regulator performance level to be configured
 - <name>-supply: phandle to the parent supply/regulator node
 - regulator-ramp-delay: ramp delay for regulator(in uV/uS)
   For hardware which supports disabling ramp rate, it should be explicitly

drivers/regulator/of_regulator.c

···
 	if (of_property_read_bool(np, "regulator-allow-bypass"))
 		constraints->valid_ops_mask |= REGULATOR_CHANGE_BYPASS;
 
+	if (of_property_read_bool(np, "regulator-allow-set-load"))
+		constraints->valid_ops_mask |= REGULATOR_CHANGE_DRMS;
+
 	ret = of_property_read_u32(np, "regulator-ramp-delay", &pval);
 	if (!ret) {
 		if (pval)