staging: mt7621-spi: Fix line over 80 characters by refactoring.

The patch fixes following checkpatch.pl issue:
WARNING : line over 80 characters
Signed-off-by: Sankalp Negi <sankalpnegi2310@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-spi/spi-mt7621.c

@@ -55,7 +55,8 @@
 #define MT7621_CPOL		BIT(4)
 #define MT7621_LSB_FIRST	BIT(3)
 
-#define RT2880_SPI_MODE_BITS	(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_CS_HIGH)
+#define RT2880_SPI_MODE_BITS	(SPI_CPOL | SPI_CPHA |		\
+				 SPI_LSB_FIRST | SPI_CS_HIGH)
 
 struct mt7621_spi;