CMSIS-NN: add kernel and unittest for int16 pooling (#1408)

Co-authored-by: Måns Nilsson <mans.nilsson@arm.com>

Change-Id: Iafcfd0c2509d23566fdbb2709796e2c210fa1083

Co-authored-by: Annie Tallund <annie.tallund@arm.com>
diff --git a/ARM.CMSIS.pdsc b/ARM.CMSIS.pdsc
index 0938273..1fba1b3 100644
--- a/ARM.CMSIS.pdsc
+++ b/ARM.CMSIS.pdsc
@@ -17,6 +17,7 @@
        - Support dilation for int8 convolution
        - Support dilation for int8 depthwise convolution
        - Support for int16 depthwise conv for reference implementation including dilation
+       - Support for int16 average and max pooling for reference implementation
       CMSIS-RTOS2:
         - RTX 5.5.4 (see revision history for details)
     </release>
@@ -2844,7 +2845,9 @@
         <file category="source" name="CMSIS/NN/Source/ConcatenationFunctions/arm_concatenation_s8_z.c"/>
         <file category="source" name="CMSIS/NN/Source/SVDFunctions/arm_svdf_s8.c"/>
         <file category="source" name="CMSIS/NN/Source/PoolingFunctions/arm_max_pool_s8.c"/>
+        <file category="source" name="CMSIS/NN/Source/PoolingFunctions/arm_max_pool_s16.c"/>
         <file category="source" name="CMSIS/NN/Source/PoolingFunctions/arm_avgpool_s8.c"/>
+        <file category="source" name="CMSIS/NN/Source/PoolingFunctions/arm_avgpool_s16.c"/>
         <file category="source" name="CMSIS/NN/Source/PoolingFunctions/arm_pool_q7_HWC.c"/>
         <file category="source" name="CMSIS/NN/Source/BasicMathFunctions/arm_elementwise_mul_s8.c"/>
         <file category="source" name="CMSIS/NN/Source/BasicMathFunctions/arm_elementwise_add_s8.c"/>