platform/chrome: cros_ec_typec: Get mux state inside configure_mux

Move the function which gets current mux state inside the
cros_typec_configure_mux() function. It is better to group those
bits of functionality together, and it makes it easier to move around
cros_typec_configure_mux() later.

While we are doing this, also inline the cros_typec_get_mux_info() inside
of cros_typec_configure_mux().

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/chrome-platform/20220208184721.1697194-3-pmalani@chromium.org/