extcon: Alter MHL-TA cable name to TA cable name

This patch alters the MHL-TA cable name to TA cable name because MHL-TA is not
standard name. The MHL-TA is MHL cable with charger cable (TA or USB). So, this
patch use the TA cable instead of MHL-TA to inform the charger cable state.
- MHL-TA -> TA

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>