One option is updating the top level make file with "$(NAME)_CFLAGS = -Wno-error=<error>" to suppress warnings as error.
Ex for suppressing "unused-variable" as error would be:
$(NAME)_CFLAGS = -Wno-error=unused-variable
Instead of selectively suppressing warnings, perhaps you could use -w to inhibit all warnings.
$(NAME)_CFLAGS = -w