IPC: Increase max size from 128 to 384

This patch increases IPC length to be sufficient for e.g. 2x 12th order
IIR configuration. This is near to minimum feasible to enable testing of
equalizers. There may be need to adjust the limit up even more later but
this is the proposal now until we know better the requirements.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

Author: singalsu

src/include/uapi/ipc.h

@@ -135,7 +135,7 @@
 #define SOF_IPC_MESSAGE_ID(x)			((x) & 0xffff)
 
 /* maximum message size for mailbox Tx/Rx */
-#define SOF_IPC_MSG_MAX_SIZE			128
+#define SOF_IPC_MSG_MAX_SIZE			384
 
 /*
  * SOF panic codes