power: supply: bq27xxx: Update comments

The URL of bq27441-g1 and bq27426 are missing and bq27520-g4 is duplicated.

Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>