drm/tegra: hdmi: sor: Fix error: variable ‘j’ set but not used

drm/tegra: hdmi: sor: Fix error: variable ‘j’ set but not used

The variable j is set, however never used in or outside the loop, thus
resulting in dead code.
Building with GCC 16 results in a build error due to
-Werror=unused-but-set-variable= enabled by default.
This patch clean up the dead code and fixes the build error.

Example build log:
drivers/gpu/drm/tegra/sor.c:1867:19: error: variable ‘j’ set but not used [-Werror=unused-but-set-variable=]
 1867 |         size_t i, j;
      |                   ^

Signed-off-by: Brahmajit Das <listout@listout.xyz>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20250901212020.3757519-1-listout@listout.xyz