dt-bindings: i2c: ce4100: Replace "ti,pcf8575" by "nxp,pcf8575"

The TI part is equivalent to the NXP part, and its compatible value is
not documented in the DT bindings.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>