i2c: muxes: pca954x: clarify enable field

The chip_desc.enable field is used only for muxes, not for switches.
Document it and remove the unused values.

Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Reviewed-by: Heiko Schocher <hs@denx.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Heiko Schocher<hs@denx.de>
1 file changed