mfd: tps65912-spi: Remove unused variable

‘rx_buf’ is not used in this function.
Signed-off-by: Sachin Kamat <sachin.kamat@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/tps65912-spi.c

@@ -32,10 +32,9 @@ static int tps65912_spi_write(struct tps65912 *tps65912, u8 addr,
 	unsigned long spi_data = 1 << 23 | addr << 15 | *data;
 	struct spi_transfer xfer;
 	struct spi_message msg;
-	u32 tx_buf, rx_buf;
+	u32 tx_buf;
 
 	tx_buf = spi_data;
-	rx_buf = 0;
 
 	xfer.tx_buf	= &tx_buf;
 	xfer.rx_buf	= NULL;