i2c: designware: Consolidate PM ops

We have the same (*) PM ops in the PCI and platform drivers.
Instead, consolidate that PM ops under exported variable and
deduplicate them.

*)
With the subtle ACPI and P-Unit behaviour differences in PCI case.
But this is not a problem as for ACPI we need to take care of the
P-Unit semaphore anyway and calling PM ops for PCI makes sense as
it might provide specific operation regions in ACPI (however there
are no known devices on market that are using it with PCI enabled I2C).
Note, the clocks are not in use in the PCI case.

Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Sanket Goswami <Sanket.Goswami@amd.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>