usb: musb: Removes compilation warning in gadget mode

Fixes compilation warning when musb is configured in gadget mode.

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/musb/omap2430.c b/drivers/usb/musb/omap2430.c
index 9d2dcb1..ce6c162 100644
--- a/drivers/usb/musb/omap2430.c
+++ b/drivers/usb/musb/omap2430.c
@@ -53,7 +53,9 @@
 {
 	struct musb	*musb = (void *)_musb;
 	unsigned long	flags;
+#ifdef CONFIG_USB_MUSB_HDRC_HCD
 	u8	power;
+#endif
 	u8	devctl;
 
 	devctl = musb_readb(musb->mregs, MUSB_DEVCTL);