PCI: rcar: Add suspend/resume

Add suspend/resume support for rcar. The resume handler reprograms the
hardware based on the software state kept in specific device structures,
so there is no need to save registers on suspend.

Link: https://lore.kernel.org/r/20200314191232.3122290-1-marek.vasut@gmail.com
Link: https://lore.kernel.org/r/20200426123148.56051-1-marek.vasut@gmail.com


Signed-off-by: Kazufumi Ikeda <kaz-ikeda@xc.jp.nec.com>
Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Simon Horman <horms+renesas@verge.net.au>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-renesas-soc@vger.kernel.org