Input: add bu21029 touch driver

Add Rohm BU21029 resistive touch panel controller support with I2C
interface.

Signed-off-by: Zhu Yi <yi.zhu5@cn.bosch.com>
Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>