gpio: pca953x: Add TI TCA9539 compatible string

Add TI TCA9539 compatible string for yet another I2C GPIO expander.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Mario Six <mario.six@gdsys.cc>
Cc: Peng Fan <van.freenix@gmail.com>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Peng Fan <peng.fan@nxp.com>