staging:rtl8192u: remove typedef of enumeration TR_SELECT - Style

To clear a checkpatch issue removed the typedef of the enumeration TR_SELECT
this should not impact runtime code as it's only a coding style change.

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