ARM: davinci: Remove unused functions from header

There are a few functions defined in the header file, but they are
not referenced by any Davinci code.  In order to make a general
function in the future with static function declarations, this
patch will remove the references all together.

Signed-off-by: Adam Ford <aford173@gmail.com>

arch/arm/mach-davinci/include/mach/da8xx-usb.h

@@ -86,7 +86,4 @@ struct da8xx_usb_regs {
 
 #define DA8XX_USB_VBUS_GPIO	(1 << 15)
 
-int usb_phy_on(void);
-void usb_phy_off(void);
-
 #endif	/* __DA8XX_MUSB_H__ */