add QSPI memory mapped mode support.  tested.  QSPI may enter and exit memory mapped mode; while in effect, other operations (e.g. command, memory) will fail with -EBUSY.

add QSPI memory mapped mode support.  tested.  QSPI may enter and exit memory mapped mode; while in effect, other operations (e.g. command, memory) will fail with -EBUSY.

VNC: Ignore client framebuffer updates if nothing has changed (we can does this because client requests incremental updates

Fixed const warning

VNC: Fixes from debug.  One issues is that VNC client is changing color formats after starting.  That is now handled.

STM32F7:  Add dummy stm32_spi.h header file to workaround some compilation issues.  Suggest by Martin Davey.

lpc4357fet256_pinconfig.h has wrong ethernet pins configuration (slow slew rate, somewhere inbuffer should be used). From Vytautas Lukenskas