dmaengine: stm32-mdma: fix chan initialization in stm32_mdma_irq_handler()

The parameter to pass back to the handler function when irq has been
requested is a struct stm32_mdma_device pointer, not a struct
stm32_mdma_chan pointer.
Even if chan is reinit later in the function, remove this wrong
initialization.

Fixes: a4ffb13c8946 ("dmaengine: Add STM32 MDMA driver")
Signed-off-by: Amelie Delaunay <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/stm32-mdma.c

···
 static irqreturn_t stm32_mdma_irq_handler(int irq, void *devid)
 {
 	struct stm32_mdma_device *dmadev = devid;
-	struct stm32_mdma_chan *chan = devid;
+	struct stm32_mdma_chan *chan;
 	u32 reg, id, ccr, ien, status;
 
 	/* Find out which channel generates the interrupt */