spi: dw: Downgrade interrupt.h to irqreturn.h where appropriate

spi-dw-mid.c along with spi-dw.h are direct users of irqreturn.h
and nothing else is being used from interrupt.h. So, switch them
to use the former instead of latter one.

While here, move the header under #ifdef CONFIG_SPI_DW_MID_DMA
in spi-dw-mid.c.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200506153025.21441-4-andriy.shevchenko@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-dw-mid.c

@@ -7,7 +7,6 @@
 
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
-#include <linux/interrupt.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/types.h>
@@ -15,6 +14,7 @@
 #include "spi-dw.h"
 
 #ifdef CONFIG_SPI_DW_MID_DMA
+#include <linux/irqreturn.h>
 #include <linux/pci.h>
 #include <linux/platform_data/dma-dw.h>
 

drivers/spi/spi-dw.h

@@ -2,7 +2,7 @@
 #ifndef DW_SPI_HEADER_H
 #define DW_SPI_HEADER_H
 
-#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
 #include <linux/io.h>
 #include <linux/scatterlist.h>