BACKPORT: extcon: Mark extcon_get_edev_name() function as exported symbol

extcon_get_edev_name() function provides client driver to request
extcon dev's name. If extcon driver and client driver are compiled
as loadable modules, extcon_get_edev_name() function symbol is not
visible to client driver. Hence mark extcon_find_edev_name() function
as exported symbol.

(cherry picked from commit 995bb1092326b8ba8fa29456c334ac6a49765ccd
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git

)
Bug: 152643506
Change-Id: Idbeed2cf45cc201d707ccbccdd043d71e3a0c23a
Signed-off-by: Mayank Rana <mrana@codeaurora.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>