drm/bridge: imx8mp-hdmi-pvi: Fix build warnings

drm/bridge: imx8mp-hdmi-pvi: Fix build warnings

Two separate build warnings were reported.  One from an
uninitialized variable, and the other from returning 0
instead of NULL from a pointer.

Fixes: 059c53e877ca ("drm/bridge: imx: add driver for HDMI TX Parallel Video Interface")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202402062134.a6CqAt3s-lkp@intel.com/
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240207002305.618499-1-aford173@gmail.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240207002305.618499-1-aford173@gmail.com