pmdomain: renesas: Adjust the waiting time to cover the worst case

Description in HWM rev0.51E, 9.4 Usage notes, page 455 tells

	"It takes several hundreds of microseconds to shutting off and
	 resuming power domain. Because actual time required for
	 shutting off and resuming depends on the status of on-board
	 power line, shutoff/resume time is not guaranteed by
	 electrical specification"

Let's assume the safe value of waiting is about 1000us.

Signed-off-by: Dien Pham <dien.pham.ry@renesas.com>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Tho Vu <tho.vu.wh@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/8734tx8b18.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>