Drop the DRM IRQ midlayer in favor of Linux IRQ interfaces. DRM's
IRQ helpers are mostly useful for UMS drivers. Modern KMS drivers
don't benefit from using it.

Vmwgfx already uses Linux IRQ functions. All that's left to replace
is the reference to struct drm_device.irq. Use irq value of struct
pci_dev instead.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210706072253.6844-1-tzimmermann@suse.de