PM / clock_ops: fix up clk prepare/unprepare count

The drivers/base/power/clock_ops.c file is causing warnings from
the clock driver (as shown below) due to failing to do a clk_prepare()
call before enabling a clock. It also fails to check the balance of
prepare/unprepare as __pm_clk_remove() do clk_disable_unprepare() call.

This bug has probably been in since commit b2476490e ("clk: introduce
the common clock framework") as the warning was part of the original
commit. It is strange that it has not been noticed (although this has
also been coupled with a failure for certain SH builds to not build the
necessary glue to use this method of controlling the clocks).

In summary, this is probably needed in several stable branches but need
advice on which ones.

On the Renesas Lager board, this causes numerous warnings of the following
and even worse the clock system will not enable clocks, causing drivers
that are in development to fail to work:

WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:883 __clk_enable+0x2c/0xa0()

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Ian Molton <ian.molton@codethink.co.uk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
PM / clock_ops: check return of clk_enable() in pm_clk_resume()

The clk_enable() call in the pm_clk_resume() call returns an error
that is not being checked. If clk_enable() fails then we should
not set the state of the clock to PCE_STATUS_ENABLED.

Note, the issue of warning the user if this fails has not been
addressed in this patch as this is not the only place the driver
calls clk_enable().

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Ian Molton <ian.molton@codethink.co.uk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
PM / clock_ops: report clock errors from clk_enable()

If clk_enable() fails, then print a message so that the user can see
what is happening instead of silently failing to enable the clock.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Ian Molton <ian.molton@codethink.co.uk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Merge branch 'pm-clk'

* pm-clk:
  PM / clock_ops: report clock errors from clk_enable()
  PM / clock_ops: check return of clk_enable() in pm_clk_resume()
  PM / clock_ops: fix up clk prepare/unprepare count