arm64: defconfig: Enable PCF857X GPIO expander

Enable the PCF857X GPIO expander which is equipped on
the PHYTEC phyBOARD-Lyra AM625.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Link: https://lore.kernel.org/r/20241003063642.2710384-1-w.egorov@phytec.de
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>