Fix stack buffer size for IPC writev messages

The stack buffer for IPC messages was 16 bytes, limiting messages to a
size of 4 (each message is 32 bit).
However, the touch screen driver is trying to send messages of size 5....

(AC: Set to 20 bytes having checked the max size allowed)
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/intel_scu_ipc.c

@@ -58,8 +58,8 @@
 
 #define IPC_BASE_ADDR     0xFF11C000	/* IPC1 base register address */
 #define IPC_MAX_ADDR      0x100		/* Maximum IPC regisers */
-#define IPC_WWBUF_SIZE    16		/* IPC Write buffer Size */
-#define IPC_RWBUF_SIZE    16		/* IPC Read buffer Size */
+#define IPC_WWBUF_SIZE    20		/* IPC Write buffer Size */
+#define IPC_RWBUF_SIZE    20		/* IPC Read buffer Size */
 #define IPC_I2C_BASE      0xFF12B000	/* I2C control register base address */
 #define IPC_I2C_MAX_ADDR  0x10		/* Maximum I2C regisers */