usb: phy: am335x-control: include appropriate header file in phy-am335x-control.c

Include header file drivers/usb/phy/am35x-phy-control.h in
phy/phy-am335x-control.c because function am335x_get_phy_control() has
its prototype declaration in drivers/usb/phy/am35x-phy-control.h.

Also, remove definition of structure phy_control because it is already
defined in the included header.

This eliminates the following warning in phy/phy-am335x-control.c:
drivers/usb/phy/phy-am335x-control.c:114:21: warning: no previous prototype for ‘am335x_get_phy_control’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <[e-mail]>
Reviewed-by: Josh Triplett <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/phy/phy-am335x-control.c

···
 #include <linux/err.h>
 #include <linux/of.h>
 #include <linux/io.h>
-
-struct phy_control {
-	void (*phy_power)(struct phy_control *phy_ctrl, u32 id, bool on);
-	void (*phy_wkup)(struct phy_control *phy_ctrl, u32 id, bool on);
-};
+#include "am35x-phy-control.h"
 
 struct am335x_control_usb {
 	struct device *dev;