tpcmv2: Fix compile error for Zephyr builds
tpcmv2: Fix compile error for Zephyr builds

Fix Type-C max source mutex for compatibility with Zephyr environment.

BUG=none
BRANCH=none
TEST=make buildall
TEST=build zephyr-chrome for volteer

Signed-off-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>
Change-Id: Ibae899b8c937e0ed673ce9661584091440d40c1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2605327
Reviewed-by: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>
Commit-Queue: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec