drivers/misc/ad525x_dpot.c: fix typo in spi write16 and write24 transfer counts

This is a bug fix.  Some SPI connected devices using 16/24 bit accesses,
previously failed, now work.

This typo slipped in after testing, during some restructuring.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Chris Verges <chrisv@cyberswitching.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/misc/ad525x_dpot-spi.c

@@ -53,13 +53,13 @@ static int write8(void *client, u8 val)
 static int write16(void *client, u8 reg, u8 val)
 {
 	u8 data[2] = {reg, val};
-	return spi_write(client, data, 1);
+	return spi_write(client, data, 2);
 }
 
 static int write24(void *client, u8 reg, u16 val)
 {
 	u8 data[3] = {reg, val >> 8, val};
-	return spi_write(client, data, 1);
+	return spi_write(client, data, 3);
 }
 
 static int read8(void *client)