v3d: use more an auxiliar devinfo

v3d: use more an auxiliar devinfo

Improve readability by using an auxiliar
        struct v3d_device_info *devinfo = &screen->devinfo;

this was triggered by the use of the v3d_X macro, where just having a
devinfo makes is more friendly. As we are here, we used it on other
places of the code.

Acked-by: Iago Toral Quiroga <itoral@igalia.com>
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23172>