arm64: dts: renesas: beacon: Fix regulator node names

arm64: dts: renesas: beacon: Fix regulator node names

Currently there are two nodes named "regulator_camera".  This causes the
former to be overwritten by the latter.

Fix this by renaming them to unique names, using the preferred hyphen
instead of an underscore.

While at it, update the name of the audio regulator (which was added in
the same commit) to use a hyphen.

Fixes: a9771f205855f28d ("arm64: dts: renesas: Introduce r8a774a1-beacon-rzg2m-kit")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/a9ac82bdf108162487289d091c53a9b3de393f13.1652263918.git.geert+renesas@glider.be