staging:rtl8192u: Rename enum label CmdID_End > CMD_ID_END - Style

Rename enum label to clear a CamelCase warning from checkpatch. This is a
simple style change and should not impact execution.

Signed-off-by: John Whitmore <johnfwhitmore@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>