CRAS: rework check for master control names.
CRAS: rework check for master control names.

To make the soon-to-come addition of checking for switches easier.

BUG=none
TEST=build and run cras on z600.

Change-Id: I7eb9b868836085600200b820f8c72971464afe35
Signed-off-by: Dylan Reid <c791bfe44996c1eed9c7149a0c5f12a86d58eb85@chromium.org>

drinkcat/adhd,drinkcat/adhd,drinkcat/adhd,drinkcat/adhd,drinkcat/adhd,drinkcat/adhd