atomisp: eliminate intel_mid_pm.h

We can do this because the only thing it is used for is identifying the
platform for power management purposes. The driver only supports Baytrail
and Cherrytrail and both of those always need the IPU to be power managed
directly not via PCI D3 states.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>