regulator: Staticize 'regulator_states' array

The 'regulator_states' array is used only in this unit and it is not
exported. Make it static.

This also fixes following sparse warning:
drivers/regulator/of_regulator.c:22:12: warning: symbol 'regulator_states' was not declared. Should it be static?
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/of_regulator.c

@@ -19,7 +19,7 @@
 
 #include "internal.h"
 
-const char *const regulator_states[PM_SUSPEND_MAX + 1] = {
+static const char *const regulator_states[PM_SUSPEND_MAX + 1] = {
 	[PM_SUSPEND_MEM]	= "regulator-state-mem",
 	[PM_SUSPEND_MAX]	= "regulator-state-disk",
 };