staging:rtl8192u: Remove member initialgain_lowerbound_state - Style

The structure 'dig' defines a member variable
'initialgain_lowerbound_state', which although initialised to false,
is never used in the code. As a result this unused member variable
has been removed.

This is a coding style change which should not impact runtime code
execution.

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