vgaarb: remove the unused irq_set_state argument to vga_client_register

All callers pass NULL as the irq_set_state argument, so remove it and
the ->irq_set_state member in struct vga_device.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210716061634.2446357-7-hch@lst.de


Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>