fixed erfinv build error as it is implemented in hcc

Change-Id: I27a512147c53f658a63fdf3e90f5e9cfac09ada8

src/math_functions.cpp

@@ -830,16 +830,6 @@ __host__ double erfcinv(double y)
     return __hip_host_erfcinv(y);
 }
 
-__host__ float erfinvf(float x)
-{
-    return __hip_host_erfinvf(x);
-}
-
-__host__ double erfinv(double x)
-{
-    return __hip_host_erfinv(x);
-}
-
 __host__ double fdivide(double x, double y)
 {
     return x/y;
@@ -949,7 +939,7 @@ __host__ void sincospi(double x, double *sptr, double *cptr)
 
 __host__ float normcdfinvf(float x)
 {
-    return std::sqrt(2) * erfinv(2*x-1);
+    return std::sqrt(2) * erfinvf(2*x-1);
 }
 
 __host__ double normcdfinv(double x)