arm_cortex_common: Add memory_barrier_dma() that emits dmb instruction.
arm_cortex_common: Add memory_barrier_dma() that emits dmb instruction.

johnkingsley/aprinter,fixator/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,fixator/aprinter,johnkingsley/aprinter,fixator/aprinter,johnkingsley/aprinter,fixator/aprinter,ambrop72/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,ambrop72/aprinter,fixator/aprinter,ambrop72/aprinter,ambrop72/aprinter,fixator/aprinter,ambrop72/aprinter