usb:composite: USB Mass Storage - storage_common.c from Linux kernel

The storage_common.c source file from v2.6.36 Linux kernel.

commit d26a6aa08b9f12b44fb1ee65625e7480d3d5bb81
Author: Michal Nazarewicz <m.nazarewicz@samsung.com>
Date:   Mon Nov 9 14:15:23 2009 +0100

USB: g_mass_storage: code cleaned up and comments updated

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Marek Vasut <marek.vasut@gmail.com>