[Makefile] Format variables to lower_snake_case

BZ: 115743

Some variables where not formatted as requested by the coding style.

Format them to lower_snake_case.

Change-Id: I31c152f161cde469bcd4c00953e95274c60868ca
Signed-off-by: Kevin Rocard <kevinx.rocard@intel.com>
Reviewed-on: http://android.intel.com:8080/115175
Reviewed-by: Denneulin, Guillaume <guillaume.denneulin@intel.com>
Reviewed-by: De Chivre, Renaud <renaud.de.chivre@intel.com>
Tested-by: Dixon, CharlesX <charlesx.dixon@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
6 files changed