pvr: Remove logic to set vk_device::alloc.
The field is being already set by vk_device_init(). Signed-off-by: Rajnesh Kanwal <rajnesh.kanwal@imgtec.com> Reviewed-by: Frank Binns <frank.binns@imgtec.com> Reviewed-by: Jason Ekstrand <jason.ekstrand@collabora.com> Part-of: <!15768>