[PATCH] drm/nouveau: check ioctl command codes better

[Satadru Pramanik]

Hello all,

I suspect this commit in 6.16-rc7 has broken acceleration with Mesa's
nouveau drivers on my machine.

glxinfo -B reports that I'm using llvmpipe.

Reverting this in 6.16-rc7 restores nouveau acceleration, and glxinfo
then reports: "OpenGL renderer string: NVE7"

inxi -G
Graphics:
  Device-1: NVIDIA GK107M [GeForce GT 750M Mac Edition] driver: nouveau
    v: kernel
  Display: wayland server: X.Org v: 24.1.8 with: Xwayland v: 24.1.8
    compositor: gnome-shell v: 48.0 driver: X: loaded: modesetting
    unloaded: fbdev,vesa dri: nouveau gpu: nouveau resolution: 2880x1800~60Hz
  API: EGL v: 1.5 drivers: nouveau,swrast
    platforms: gbm,wayland,x11,surfaceless,device
  API: OpenGL v: 4.5 compat-v: 4.3 vendor: mesa
    v: 25.2.0~rc1+git2507191056.03f67b52319~p~mesarc0 renderer: NVE7
  API: Vulkan v: 1.4.304 drivers: N/A surfaces: xcb,xlib,wayland
  Info: Tools: api: eglinfo, glxinfo, vulkaninfo x11: xdriinfo, xdpyinfo,
    xprop, xrandr

Best,
Satadru Pramanik