usb: host: ehci: allow ehci_* symbols to be unused

not all platforms will use all of those ehci_*
symbols on their hc_driver structure. Sometimes
we might need to provide a modified version of
a certain method or not provide it at all, as is
the case with OMAPs which don't support port handoff
feature.

Whenever we compile a kernel for an OMAP board with
EHCI enabled, we get compile warnings:

drivers/usb/host/ehci-hub.c:1079: warning: 'ehci_relinquish_port' \
	defined but not used
drivers/usb/host/ehci-hub.c:1088: warning: 'ehci_port_handed_over' \
	defined but not used

In order to cleanup those warnings, we're adding
__maybe_unused annotation to those functions.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-hub.c

@@ -107,7 +107,7 @@ static void ehci_handover_companion_ports(struct ehci_hcd *ehci)
 	ehci->owned_ports = 0;
 }
 
-static int ehci_port_change(struct ehci_hcd *ehci)
+static int __maybe_unused ehci_port_change(struct ehci_hcd *ehci)
 {
 	int i = HCS_N_PORTS(ehci->hcs_params);
 
@@ -1076,7 +1076,8 @@ static int ehci_hub_control (
 	return retval;
 }
 
-static void ehci_relinquish_port(struct usb_hcd *hcd, int portnum)
+static void __maybe_unused ehci_relinquish_port(struct usb_hcd *hcd,
+		int portnum)
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci(hcd);
 
@@ -1085,7 +1086,8 @@ static void ehci_relinquish_port(struct usb_hcd *hcd, int portnum)
 	set_owner(ehci, --portnum, PORT_OWNER);
 }
 
-static int ehci_port_handed_over(struct usb_hcd *hcd, int portnum)
+static int __maybe_unused ehci_port_handed_over(struct usb_hcd *hcd,
+		int portnum)
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci(hcd);
 	u32 __iomem		*reg;