arm64: dts: renesas: Remove use of ARCH_R8A7795

CONFIG_ARCH_R8A7795 was split in CONFIG_ARCH_R8A77950 and
CONFIG_ARCH_R8A77951 in commit b925adfc ("soc: renesas: Add
ARCH_R8A7795[01] for existing R-Car H3"), so its users can be removed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200218112414.5591-1-geert+renesas@glider.be