kernel: rename reserved 'exp' symbol

This symbol is reserved and usage of reserved symbols violates the
coding guidelines. (MISRA 21.2)

NAME
       exp, expf, expl - base-e exponential function

SYNOPSIS
       #include <math.h>

       double exp(double x);

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
1 file changed