iwlwifi: fix suspend/resume and its usage of pci saved state

Here we do two things:

First, revert "iwlwifi: save PCI state before suspend, restore after
resume".  That misguided patch led to being unable to use iwlwifi
devices after resume.

Next, indicate to PCI driver that the saved PCI state is valid during suspend.

We restore PCI state and enable the device when network interface is created,
similarly PCI state is saved and the device is disabled when network interface
is removed. Thus, when .suspend is called the PCI state is saved and device
is disabled. This is the case even if an interface is never created as PCI
state is saved and device disabled during .probe.

PCI driver assumes PCI state is saved in .suspend. Saving the state at this
time will save state of disabled device and thus cause problems during
resume (resuming a disabled device). We thus indicate directly to PCI
driver that current PCI saved state is valid.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Alex Riesen <fork0@users.sf.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>