extcon: Fix kernel doc of property fields to avoid warnings

extcon: Fix kernel doc of property fields to avoid warnings

BugLink: https://bugs.launchpad.net/bugs/2034469
[ Upstream commit 7e77e0b7a9f4cdf91cb0950749b40c840ea63efc ]

Kernel documentation has to be synchronized with a code, otherwise
the validator is not happy:

     Function parameter or member 'usb_propval' not described in 'extcon_cable'
     Function parameter or member 'chg_propval' not described in 'extcon_cable'
     Function parameter or member 'jack_propval' not described in 'extcon_cable'
     Function parameter or member 'disp_propval' not described in 'extcon_cable'

Describe the fields added in the past.

Fixes: 067c1652e7a7 ("extcon: Add the support for extcon property according to extcon type")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>