Revert "Remove workaround of setting CORE_OPTIMIZATION_LEVEL to -Ofast"

This reverts commit 236a00d1125267be32d8f745d8d49e3e73251151.

Reason for revert: Patch caused regression failures that need to be addressed.

Change-Id: I2e79a16b8e5fa61d8b313ad7808cfd8845e4275a
diff --git a/tflite_micro.cmake b/tflite_micro.cmake
index 56f54a4..083acbd 100644
--- a/tflite_micro.cmake
+++ b/tflite_micro.cmake
@@ -72,6 +72,7 @@
                           $<$<BOOL:${FLOAT}>:FLOAT=${FLOAT}>
                           BUILD_TYPE=${TFLU_BUILD_TYPE}
                           $<$<BOOL:${TFLU_OPTIMIZATION_LEVEL}>:KERNEL_OPTIMIZATION_LEVEL=${TFLU_OPTIMIZATION_LEVEL}>
+                          $<$<BOOL:${TFLU_OPTIMIZATION_LEVEL}>:CORE_OPTIMIZATION_LEVEL=${TFLU_OPTIMIZATION_LEVEL}>
                           CMSIS_PATH=${CMSIS_PATH}
                           ETHOSU_DRIVER_PATH=${CORE_DRIVER_PATH}
                           ETHOSU_DRIVER_LIBS=${TFLU_ETHOSU_LIBS}