gpu/drm: tegra: Fix support for Linux v6.12

In Linux v6.12, commit 641bb4394f40 ("fs: move FMODE_UNSIGNED_OFFSET to
fop_flags") moves the setting of the FMODE_UNSIGNED_OFFSET into the
various drivers and renames this flag. This change is causing various
tests to fail because opening the DRM device is failing.

Use the presence of the new FOP_UNSIGNED_OFFSET flag in the kernel to
determine if we need to set this flag in the Tegra DRM driver.

Bug 4876974

Change-Id: Ie72a9340187b1c206f0cda6d7e3dab44d603a41c
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3269063
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>

drivers/gpu/drm/tegra/drm.c

@@ -823,6 +823,9 @@ static const struct file_operations tegra_drm_fops = {
 	.read = drm_read,
 	.compat_ioctl = drm_compat_ioctl,
 	.llseek = noop_llseek,
+#if defined(NV_FOP_UNSIGNED_OFFSET_PRESENT) /* Linux v6.12 */
+	.fop_flags = FOP_UNSIGNED_OFFSET,
+#endif
 };
 
 static int tegra_drm_context_cleanup(int id, void *p, void *data)