extcon: arizona: Remove the setting of device name

This patch removes the setting of device name. Instead, extcon_dev_register()
set the device name such as 'extcon[number]' naming method.
- /sys/class/extcon/Headset Jack -> /sys/class/extcon/extcon[number]

Cc: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>