usb: composite convert __set_bit to generic_set_bit

Compiling the f_mass_storage driver for an x86 target results in a
compilation error as set_bit and clear_bit are provided by bitops.h

To address that situation we discussed on the list moving to
genetic_set_bit() instead.

Doing a quick grep for similar situations in drivers/usb shows that the
composite device is using __set_bit().

This patch switches over to generic_set_bit to maintain consistency between
the two gadget drivers.

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Marek Vasut <marex@denx.de>

drivers/usb/gadget/composite.c

@@ -378,7 +378,7 @@ static int set_config(struct usb_composite_dev *cdev,
 			ep = (struct usb_endpoint_descriptor *)*descriptors;
 			addr = ((ep->bEndpointAddress & 0x80) >> 3)
 			     |	(ep->bEndpointAddress & 0x0f);
-			__set_bit(addr, f->endpoints);
+			generic_set_bit(addr, f->endpoints);
 		}
 
 		result = f->set_alt(f, tmp, 0);