Current, the dewake_scanline variable is defined as unsigned int,
an unsigned int variable that is always greater than or equal to 0.
when _intel_dsb_commit function is called by intel_dsb_commit function,
the dewake_scanline variable may have an int value.
So the dewake_scanline variable is necessary to defined as an int.

Fixes: f83b94d2 ("drm/i915/dsb: Use DEwake to combat PkgC latency")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202310052201.AnVbpgPr-lkp@intel.com/
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: heminhong <heminhong@kylinos.cn>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231114024341.14524-1-heminhong@kylinos.cn