i2c: muxes: pca954x: Use reset controller only

Fallback to legacy reset-gpios is no more needed, because the framework
can use reset-gpios properity now as well.

Signed-off-by: Wojciech Siudy <wojciech.siudy@nokia.com>
[wsa: fixed whitespace issue]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>