mmc: sdhci-of-esdhc: remove platform_suspend/platform_resume callbacks

We don't need these hooks in order to insert code in these paths, we
can just provide our own handlers and call the main sdhci handlers as
appropriate.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Markus Pargmann <mpa@pengutronix.de>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>