Staging: Merge ENE UB6250 SD card codes from keucr to drivers/usb/storage

The usb portion of this driver can now go into drivers/usb/storage.
This leaves the non-usb portion of the code still in staging.

Signed-off-by: Huajun Li <huajun.li.lee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>