drivers/usb_mux: Allow inverted polarity on muxes

This adds a feature for USB-C muxes to be inverted with respect to cable
orientation. This effectively adds support for the case where CC1/CC2
are swapped.

BRANCH=none
BUG=b:240938782
TEST=USB3 and DP works on ghost MLB port with rest of patchset

Change-Id: I1441810754078c51ff46f84106aa33e8eb813eb0
Signed-off-by: Caveh Jalali <caveh@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3818926
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Boris Mittelberg <bmbm@google.com>
diff --git a/src/platform/ec b/src/platform/ec
index 6e83275..a0befd9 160000
--- a/src/platform/ec
+++ b/src/platform/ec
@@ -1 +1 @@
-Subproject commit 6e832755e66110947f9dd29686163dc108ba40a6
+Subproject commit a0befd973ce613e65c474efd365a73eb54f1d911