[feat][nmsis] add nmsis component and nn,dsp demo

examples/dsp/FastMathFunctions_squareRootPart/exp.c

@@ -0,0 +1,22 @@
+#include "ref.h"
+
+void ref_vexp_f32(
+  const float32_t * pSrc,
+        float32_t * pDst,
+        uint32_t blockSize)
+{
+   uint32_t blkCnt; 
+
+   blkCnt = blockSize;
+
+   while (blkCnt > 0U)
+   {
+      /* C = log(A) */
+  
+      /* Calculate log and store result in destination buffer. */
+      *pDst++ = expf(*pSrc++);
+  
+      /* Decrement loop counter */
+      blkCnt--;
+   }
+}