Moving CMSIS-NN to separate repository

Change-Id: I71637859e96d799482c74a8f55f7f792c2ed606b
diff --git a/.gitignore b/.gitignore
index c90f033..c58c1f4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 /build
 /core_driver
 /cmsis
+/cmsis-nn
 /openamp
 /rtos/freertos
 /rtos/threadx