Bluetooth: btuart_cs: remove obsolete header

Use <linux/io.h> instead of <asm/io.h>, fixes checkpatch
Warning;

Signed-off-by: Prasanna Karthik <mkarthi3@visteon.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btuart_cs.c

@@ -38,7 +38,7 @@
 #include <linux/serial.h>
 #include <linux/serial_reg.h>
 #include <linux/bitops.h>
-#include <asm/io.h>
+#include <linux/io.h>
 
 #include <pcmcia/cistpl.h>
 #include <pcmcia/ciscode.h>