USB: core endpoint: Fix Coding Styles

Fixed coding styles in the core usb endpoint.

Signed-off-by: Carlos Sánchez Acosta <csanchez@neurowork.net>
Signed-off-by: Alejandro Sánchez Acosta <asanchez@neurowork.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>