usb: typec: tcpm: Use LE to CPU conversion when accessing msg->header

Sparse is not happy about strict type handling:
  .../typec/tcpm/tcpm.c:2720:27: warning: restricted __le16 degrades to integer
  .../typec/tcpm/tcpm.c:2814:32: warning: restricted __le16 degrades to integer

Fix this by converting LE to CPU before use.

Fixes: ae8a2ca8 ("usb: typec: Group all TCPCI/TCPM code together")
Fixes: 64f7c494

 ("typec: tcpm: Add support for sink PPS related messages")
Cc: stable <stable@vger.kernel.org>
Cc: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210519100358.64018-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>