mmc: renesas_sdhi: Add suspend/resume hooks

mmc: renesas_sdhi: Add suspend/resume hooks

Add suspend/resume hooks which assert/deassert the reset signals, along
with forcing runtime suspend/resume. This allows using the driver in
scenarios where the resume is done with the help of bootloader and the
bootloader disables the SDHI clocks, resets, IRQs before passing execution
to Linux.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>