ARM: OMAP: DMA: Don't mark channel active in omap_enable_channel_irq

Channel should be marked active only when DMA is really started. Otherwise
just omap_request_dma, omap_dma_link_lch and omap_dma_unlink_lch will cause
incorrect dump_stack().
Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/dma.c

@@ -501,8 +501,6 @@ static inline void omap_enable_channel_irq(int lch)
 
 	/* Enable some nice interrupts. */
 	OMAP_DMA_CICR_REG(lch) = dma_chan[lch].enabled_irqs;
-
-	dma_chan[lch].flags |= OMAP_DMA_ACTIVE;
 }
 
 static void omap_disable_channel_irq(int lch)