mfd: Add devices for WM831x clocking module

With the new generic clk API that should appear at some point we should be
able to support the clocking sensibly in Linux.

Signed-off-by: Mark Brown <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/wm831x-core.c

···
 		.resources = wm831x_dcdc4_resources,
 	},
 	{
+		.name = "wm831x-clk",
+	},
+	{
 		.name = "wm831x-epe",
 		.id = 1,
 	},
···
 		.resources = wm831x_dcdc4_resources,
 	},
 	{
+		.name = "wm831x-clk",
+	},
+	{
 		.name = "wm831x-epe",
 		.id = 1,
 	},
···
 		.id = 4,
 		.num_resources = ARRAY_SIZE(wm831x_dcdc4_resources),
 		.resources = wm831x_dcdc4_resources,
+	},
+	{
+		.name = "wm831x-clk",
 	},
 	{
 		.name = "wm831x-epe",
···
 		.id = 4,
 		.num_resources = ARRAY_SIZE(wm8320_dcdc4_buck_resources),
 		.resources = wm8320_dcdc4_buck_resources,
+	},
+	{
+		.name = "wm831x-clk",
 	},
 	{
 		.name = "wm831x-gpio",