arm: dts: mt7623: add lima related regulator

GPU needs additional regulator, add it to devicetree of bpi-r2

Signed-off-by: Alex Ryabchenko <d3adme4t@gmail.com>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20200904110002.88966-5-linux@fw-web.de
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>