spi: Kill superfluous cast in spi_w8r16()

spi_write_then_read() takes a "void *" for rxbuf, so there's no need to
cast the buffer pointer to "u8 *".

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

include/linux/spi/spi.h

@@ -847,7 +847,7 @@ static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd)
 	ssize_t			status;
 	u16			result;
 
-	status = spi_write_then_read(spi, &cmd, 1, (u8 *) &result, 2);
+	status = spi_write_then_read(spi, &cmd, 1, &result, 2);
 
 	/* return negative errno or unsigned value */
 	return (status < 0) ? status : result;