Fixed compilation errors when compiling with -O0

drivers/display_bitsboard.cpp

drivers/display_mp3v2.cpp

drivers/display_oledboard2.cpp

drivers/display_qt.cpp

drivers/display_redbull_v2.cpp

drivers/display_sony-newman.cpp

drivers/display_st7735.cpp

drivers/display_stm3210e-eval.cpp

drivers/display_stm32f4discovery.cpp

drivers/display_strive.cpp

drivers/display_win.cpp