arm: dts: mt7623: disable home key on Bananapi BPI-R2

There's no home key on Bananapi BPI-R2. Disable it.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20230212121354.44590-1-arinc.unal@arinc9.com
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>