In some corner cases downgrade of the superspeed typec device(e.g. Dell
typec Dock, apple dongle) was seen because before the SOC mux configuration
finishes, EC starts configuring the next mux state.

With this change, once the SOC mux is configured, kernel will send an
acknowledgment to EC via Host command EC_CMD_USB_PD_MUX_ACK [1].
After sending the host event EC will wait for the acknowledgment from
kernel before starting the PD negotiation for the next mux state. This
helps to have a framework to build better error handling along with the
synchronization of timing sensitive mux states.

This change also brings in corresponding EC header updates from the EC code
base [1].

[1]:
https://chromium.googlesource.com/chromiumos/platform/ec/+/refs/heads/master/include/ec_commands.hSigned-off-by: NUtkarsh Patel <utkarsh.h.patel@intel.com>
Reviewed-by: NPrashant Malani <pmalani@chromium.org>
Signed-off-by: NBenson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20201210060903.2205-3-utkarsh.h.patel@intel.com