drm/bridge: imx93-mipi-dsi: Fix a couple of building warnings

Fix a couple of building warnings on used uninitialized 'best_m' and
'best_n' local variables by initializing 'best_m' to zero and 'best_n'
to UINT_MAX.  This makes compiler happy only.  No functional change.

Fixes: ce62f8ea ("drm/bridge: imx: Add i.MX93 MIPI DSI support")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311151746.f7u7dzbZ-lkp@intel.com/


Signed-off-by: Liu Ying <victor.liu@nxp.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231123051807.3818342-1-victor.liu@nxp.com