wl1251: add power callback to wl1251_if_operations

Call interface specific power callback before calling board specific
one. Also allow that callback to fail. This is how it's done for
wl1271 and will be used for runtime_pm support.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Acked-by: Kalle Valo <kvalo@adurom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/wl1251/wl1251.h b/drivers/net/wireless/wl1251/wl1251.h
index e113d4c..13fbeec 100644
--- a/drivers/net/wireless/wl1251/wl1251.h
+++ b/drivers/net/wireless/wl1251/wl1251.h
@@ -256,6 +256,7 @@
 	void (*write)(struct wl1251 *wl, int addr, void *buf, size_t len);
 	void (*read_elp)(struct wl1251 *wl, int addr, u32 *val);
 	void (*write_elp)(struct wl1251 *wl, int addr, u32 val);
+	int  (*power)(struct wl1251 *wl, bool enable);
 	void (*reset)(struct wl1251 *wl);
 	void (*enable_irq)(struct wl1251 *wl);
 	void (*disable_irq)(struct wl1251 *wl);