We don't really need to use different mac colors when adding mac
contexts, because they're not used anywhere.  In fact, the firmware
doesn't accept 255 as a valid color, so we get into a SYSASSERT 0x3401
when we reach that.

Remove the color increment to use always zero and avoid reaching 255.

CC: <stable@vger.kernel.org> [3.10+]
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>