Zephyr: Patch Zephyr CMakeLists with exponential source files

In Zephyr CMakeLists, add exponential source files to facilitate
the compilation of math C and HiFi code.

Signed-off-by: shastry <malladi.sastry@intel.com>

Author: singalsu

zephyr/CMakeLists.txt

@@ -370,6 +370,8 @@ zephyr_library_sources(
 	${SOF_MATH_PATH}/decibels.c
 	${SOF_MATH_PATH}/numbers.c
 	${SOF_MATH_PATH}/trig.c
+	${SOF_MATH_PATH}/exp_fcn.c
+	${SOF_MATH_PATH}/exp_fcn_hifi.c
 
 	# SOF library - parts to transition to Zephyr over time
 	${SOF_LIB_PATH}/clk.c