spi: spi-fsl-dspi: Reduce indentation level in dspi_interrupt

If the entire function depends on the SPI status register having the
interrupt bits asserted, then just check it and exit early if those bits
aren't set (such as in the case of the shared IRQ being triggered for
the other peripheral). Cosmetic patch.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20190822211514.19288-2-olteanv@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-dspi.c

@@ -658,8 +658,9 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 	regmap_read(dspi->regmap, SPI_SR, &spi_sr);
 	regmap_write(dspi->regmap, SPI_SR, spi_sr);
 
+	if (!(spi_sr & (SPI_SR_EOQF | SPI_SR_TCFQF)))
+		return IRQ_HANDLED;
 
-	if (spi_sr & (SPI_SR_EOQF | SPI_SR_TCFQF)) {
 	/* Get transfer counter (in number of SPI transfers). It was
 	 * reset to 0 when transfer(s) were started.
 	 */
@@ -685,7 +686,9 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 	if (!dspi->len) {
 		dspi->waitflags = 1;
 		wake_up_interruptible(&dspi->waitq);
-		} else {
+		return IRQ_HANDLED;
+	}
+
 	switch (trans_mode) {
 	case DSPI_EOQ_MODE:
 		dspi_eoq_write(dspi);
@@ -698,8 +701,6 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 			"unsupported trans_mode %u\n",
 			trans_mode);
 	}
-		}
-	}
 
 	return IRQ_HANDLED;
 }