Documentation/spi/* compile warning fix

Fix this warning:

Documentation/spi/spidev_fdx.c: In function `do_msg':
Documentation/spi/spidev_fdx.c:61: warning: cast from pointer to integer of different size
Documentation/spi/spidev_fdx.c:64: warning: cast from pointer to integer of different size

buf should be unsigned long to match native arch on 32-bit x86 compile.

Signed-off-by: Prarit Bhargava <[e-mail]>
Signed-off-by: Grant Likely <[e-mail]>

Documentation/spi/spidev_fdx.c

···
 		len = sizeof buf;
 
 	buf[0] = 0xaa;
-	xfer[0].tx_buf = (__u64) buf;
+	xfer[0].tx_buf = (unsigned long)buf;
 	xfer[0].len = 1;
 
-	xfer[1].rx_buf = (__u64) buf;
+	xfer[1].rx_buf = (unsigned long) buf;
 	xfer[1].len = len;
 
 	status = ioctl(fd, SPI_IOC_MESSAGE(2), xfer);