--phy-test mode MCS selection

Description :

in phy-test mode MCS configuration passed on the command line is not tacking into account. MCS00 is always selected.

Impact :

--phy-test non regression tests fail except for MCS00

Impacted version :

Since harmony merge

Correction:

A fix is ready for code review on 0277475b branch bugfix-12-phy-test_mode_MCS_selection