iwlagn: move PCI related operations from probe and remove to PCI layer

Since we have now a PCI layer, all the init and deinit code that is PCI
related should move to there.

Also move the IO functions: read8/read32/write32. They need hw_base which
is killed from priv.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>