drm/amd/display: Correct enum typo

This commit just replaces dc_interrupt_po*r*larity with its correct
name, which is dc_interrupt_polarity.

Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>