Increase message timeout

Bump the hardcoded timeout value to allow for userspaces process to
be scheduled and receive the response from the capabilities request.

Change-Id: Ia2c8a0554870cf8470a2bb40bf8ed450c10f8446
diff --git a/kernel/ethosu_device.c b/kernel/ethosu_device.c
index 13c30f6..e6f1e80 100644
--- a/kernel/ethosu_device.c
+++ b/kernel/ethosu_device.c
@@ -46,7 +46,7 @@
 
 #define DMA_ADDR_BITS 32 /* Number of address bits */
 
-#define CAPABILITIES_RESP_TIMEOUT_MS 100
+#define CAPABILITIES_RESP_TIMEOUT_MS 2000
 
 /****************************************************************************
  * Types