Revert "remoteproc: Add support for runtime PM"

This reverts commit a99a37f6

.

Removing PM runtime operations from the remoteproc core in order to:

1) Keep all power management operations in platform drivers.  That way we
do not loose flexibility in an area that is very HW specific.

2) Avoid making the support for remote processor managed by external
entities more complex that it already is.

3) Fix regression introduced for the Omap remoteproc driver.

Acked-by: Suman Anna <s-anna@ti.com>
Tested-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200630163118.3830422-3-mathieu.poirier@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>