arm64: dts: renesas: r8a779a0: Fix PMU interrupt

Should use PPI No.7 for the PMU. Otherwise, the perf command didn't
show any information.

Fixes: 834c310f ("arm64: dts: renesas: Add Renesas R8A779A0 SoC support")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20210325041949.925777-1-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>