video: Implement continuous screen refresh for SmartLCD into mxsfb

video: Implement continuous screen refresh for SmartLCD into mxsfb

The LCDIF interface doesn't give us any means to do continuous refresh
when driving a SmartLCD. To work this around, we produce a special
circular DMA descriptor, which only writes the HW_LCDIF_CTRL0 register
and sets the RUN bit.

Signed-off-by: Marek Vasut <[email protected]>
Cc: Anatolij Gustschin <[email protected]>
Cc: Fabio Estevam <[email protected]>
Cc: Otavio Salvador <[email protected]>
Cc: Stefano Babic <[email protected]>