extcon: palmas: explicitly set edev name as node name

commit ca488 (extcon: of: Remove unnecessary function call by using the
name of device_node) started using node name instead of device name
to get the extcon device. This breaks dwc3-omap since it's not able to
get the extcon device anymore. Fixed it by setting edev name of
palmas to be the same as its node name.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reported-by: Felipe Balbi <balbi@ti.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>