drm/cirrus: Use non-hybrid PCI devres API

cirrus enables its PCI device with pcim_enable_device(). This,
implicitly, switches the function pci_request_regions() into managed
mode, where it becomes a devres function.

The PCI subsystem wants to remove this hybrid nature from its
interfaces. To do so, users of the aforementioned combination of
functions must be ported to non-hybrid functions.

Replace the call to sometimes-managed pci_request_regions() with one to
the always-managed pcim_request_all_regions().

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://lore.kernel.org/r/20250417094009.29297-2-phasta@kernel.org