extcon : register for cable interest by cable name

There are some scnearios where a driver/framework needs to register
interest for a particular cable without specifying the extcon device
name. One such scenario is charger notifications. The platform will
have charger cabel which will be bound to any extcon device. It's
not mandatory for the charger driver to know which extcon device
it should use. This patch enables the support for registering
interest for a cable just by cable name wihtout specifying the
extcon device name

Signed-off-by: Jenny TC <jenny.tc@intel.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>

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Kernel-doc comment added by MyungJoo Ham