staging: mt7621-spi: Add a space before open paranthesis.

The patch fixes following checkpatch.pl issue:
ERROR : space required before the open parenthesis
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

@@ -140,7 +140,7 @@ static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
 		reg |= MT7621_LSB_FIRST;
 
 	reg &= ~(MT7621_CPHA | MT7621_CPOL);
-	switch(spi->mode & (SPI_CPOL | SPI_CPHA)) {
+	switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
 	case SPI_MODE_0:
 		break;
 	case SPI_MODE_1: