nouveau/ws: remove the drm.h header

It can cause compilation issues on Arch, there is a workaround by
including it as <drm.h> but this solution is simpler.

Signed-off-by: Yusuf Khan <yusisamerican@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24326>

src/nouveau/winsys/nouveau_context.c

@@ -1,10 +1,9 @@
 #include "nouveau_context.h"
 
-#include <drm/drm.h>
+#include <xf86drm.h>
 #include <errno.h>
 #include <nouveau_drm.h>
 #include <nouveau/nvif/ioctl.h>
-#include <xf86drm.h>
 
 #include "nouveau_device.h"
 

src/nouveau/winsys/nouveau_device.c

@@ -1,11 +1,10 @@
 #include "nouveau_device.h"
 
-#include <drm/drm.h>
+#include <xf86drm.h>
 #include <nouveau_drm.h>
 #include <nouveau/nvif/ioctl.h>
 #include <nvif/cl0080.h>
 #include <nvif/class.h>
-#include <xf86drm.h>
 
 #include "util/u_debug.h"
 #include "util/os_file.h"