dmaengine: moxart: fix kconfig unmet direct dependencies

We have unmet direct dependencies as DMA_SUN4I selects DMA_OF so remove the
selection

warning: (DMA_SUN4I && MOXART_DMA && STM32_DMA) selects DMA_OF which has
unmet direct dependencies (DMADEVICES && OF)

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>