usb-devices: correctly quote driver path

Some drivers have a name containing spaces. This causes quoting issues:

  + '[' -L /sys/bus/usb/devices/usb1/1-1/1-1.4/1-1.4.1/1-1.4.1:1.0/driver ']'
  ++ readlink /sys/bus/usb/devices/usb1/1-1/1-1.4/1-1.4.1/1-1.4.1:1.0/driver
  + driver='../../../../../../../../bus/usb/drivers/MOSCHIP usb-ethernet driver'
  ++ basename ../../../../../../../../bus/usb/drivers/MOSCHIP usb-ethernet driver
  basename: extra operand `driver'
  Try `basename --help' for more information.
  + driver=

Reported-by: Vincent Smeets <Vincent.VSmeets@GMail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>