QGCQFileDialog: Avoid QString initialization of empty string
QGCQFileDialog: Avoid QString initialization of empty string

Signed-off-by: Patrick José Pereira <c2b7559029b4032a4ce95718d7d3bc36c8a1d7c1@gmail.com>

Hunter522/qgroundcontrol,Hunter522/qgroundcontrol,Hunter522/qgroundcontrol,Hunter522/qgroundcontrol,Hunter522/qgroundcontrol,Hunter522/qgroundcontrol