USB: usb-storage: remove WARN from last-sector hacks

This patch (as1201) removes the WARN() from the last-sector hacks in
usb-storage, thereby making the code match the version now in
.27-stable and .28-stable.  The WARN() isn't needed, since there is no
longer any intention of assuming that all storage devices have an even
number of sectors, and it annoys users for no good reason.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>