This reverts commit 7ff21319.

It turns out that the above commit introduces other problems. For example,
calling pm_runtime_set_active() must not be done prior calling
pm_runtime_enable() as that makes it fail. This leads to additional
problems, such as clock enables being wrongly balanced.

Rather than fixing the problem on top, let's start over by doing a revert.

Fixes: 7ff21319 ("mmc: tmio: move runtime PM enablement to the driver implementations")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>