drm/nouveau/pci: switch to instanced constructor

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/pci: implement pcie speed change for kepler+

v2: rename functions
v3: remove pcie2 accessors
v6: fix alignement and line width, also remove useless code

Signed-off-by: Karol Herbst <nouveau@karolherbst.de>

drm/nouveau/pci: add gk104 variant

v2: change email used in header
v4: change Copyright information
v5: revert Copyright changes

Signed-off-by: Karol Herbst <nouveau@karolherbst.de>