Revert "blackfin: dma: current count mmr is read only"

curr_x_count/curr_y_count need to be cleared here, keep this workaround

This reverts commit dfb02f95f5430e47d0c49adbc4469d08eea38b94.
Signed-off-by: NSteven Miao <realmz6@gmail.com>

arch/blackfin/include/asm/dma.h

@@ -316,6 +316,8 @@ static inline void disable_dma(unsigned int channel)
 }
 static inline void enable_dma(unsigned int channel)
 {
+	dma_ch[channel].regs->curr_x_count = 0;
+	dma_ch[channel].regs->curr_y_count = 0;
 	dma_ch[channel].regs->cfg |= DMAEN;
 }
 int set_dma_callback(unsigned int channel, irq_handler_t callback, void *data);