Remove -mmma again (reduntant with cpu=power10) and add override statements

Author: martin-frbg

Makefile.power

@@ -10,8 +10,8 @@ USE_OPENMP = 1
 endif
 
 ifeq ($(CORE), POWER10)
-COMMON_OPT += -Ofast -mcpu=power10 -mtune=power10 -mvsx -mmma  -fno-fast-math
-FCOMMON_OPT += -O2 -frecursive -mcpu=power10 -mtune=power10  -fno-fast-math
+override COMMON_OPT += -Ofast -mcpu=power10 -mtune=power10 -mvsx -fno-fast-math
+override FCOMMON_OPT += -O2 -frecursive -mcpu=power10 -mtune=power10  -fno-fast-math
 endif
 
 ifeq ($(CORE), POWER9)