Staging: emxx_udc: Remove argument test from function

This patch removes the test statement for an argument to  _nbu2ss_pullup
function, for it can't be null due to previous derefrences.

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>