panvk: correct VkPhysicalDeviceProperties::deviceName

We currently report a deviceName as e.g. "Mali-G610 (Panfrost)", but
panfrost has nothing to di with the physical device, and the suffix
doesn't belong there at all.

So let's remove that suffix from PanVK. This results in output like this
from vulkaninfo:

---8<---
VkPhysicalDeviceProperties:
---------------------------
        apiVersion        = 1.1.305 (4198705)
        driverVersion     = 25.0.99 (104857699)
        vendorID          = 0x13b5
        deviceID          = 0xa8670000
        deviceType        = PHYSICAL_DEVICE_TYPE_INTEGRATED_GPU
        deviceName        = Mali-G610
        pipelineCacheUUID = <snip>
---8<---

We already sort of namedrop Panfrost in the driver properties:

---8<---
VkPhysicalDeviceDriverPropertiesKHR:
------------------------------------
        driverID        = DRIVER_ID_MESA_PANVK
        driverName      = panvk
        driverInfo      = Mesa 25.1.0-devel (git-136dd9f9)
        conformanceVersion:
                major    = 1
                minor    = 4
                subminor = 1
                patch    = 2
---8<---

While this might techically speaking be a regression, PanVK has been
marked as experimental until Mesa 25.0. But to reduce the risk of people
starting to depend on this behavior, let's also backport this change to
the 25.0 release.

The patch looks a bit funny, because we add the " (Panfrost)"-suffix in
common code, and this moves it to the Gallium driver. But effectively,
this means PanVK is the only driver that sees a change of behavior.

Backport-to: 25.0
Reviewed-by: John Anthony <john.anthony@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <!33972>