[target][stm32746g-eval2] add cache flushing routine to lcd updates
[target][stm32746g-eval2] add cache flushing routine to lcd updates

srodrig1/lk,nvll/lk,minglun-tsai/lk,littlekernel/lk,skabet/lk,travisg/lk,sndnvaps/lk,hollanderic/lkstuff,travisg/lk,srodrig1/lk,ErikCorryGoogle/lk,sndnvaps/lk,sndnvaps/lk,srodrig1/lk,littlekernel/lk,srodrig1/lk,minglun-tsai/lk,ErikCorryGoogle/lk,littlekernel/lk,skabet/lk,srodrig1/lk,skabet/lk,skabet/lk,minglun-tsai/lk,ErikCorryGoogle/lk,sndnvaps/lk,hollanderic/lkstuff,hollanderic/lkstuff,ErikCorryGoogle/lk,nvll/lk,travisg/lk,sndnvaps/lk,nvll/lk,nvll/lk,littlekernel/lk,nvll/lk,minglun-tsai/lk,travisg/lk,hollanderic/lkstuff,skabet/lk