drm/amd/display: Fix possible overflow in integer multiplication

[WHAT & HOW]
Integer multiplies integer may overflow in context that expects an
expression of unsigned long long (64 bits). This can be fixed by casting
integer to unsigned long long to force 64 bits results.

This fixes 2 OVERFLOW_BEFORE_WIDEN issues reported by Coverity.
Signed-off-by: Alex Hung <alex.hung@amd.com>
Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/resource/dcn32/dcn32_resource_helpers.c

@@ -663,7 +663,7 @@ bool dcn32_subvp_drr_admissable(struct dc *dc, struct dc_state *context)
 
 				subvp_disallow |= disallow_subvp_in_active_plus_blank(pipe);
 				refresh_rate = (pipe->stream->timing.pix_clk_100hz * (uint64_t)100 +
-					pipe->stream->timing.v_total * pipe->stream->timing.h_total - (uint64_t)1);
+					pipe->stream->timing.v_total * (unsigned long long)pipe->stream->timing.h_total - (uint64_t)1);
 				refresh_rate = div_u64(refresh_rate, pipe->stream->timing.v_total);
 				refresh_rate = div_u64(refresh_rate, pipe->stream->timing.h_total);
 			}
@@ -724,7 +724,7 @@ bool dcn32_subvp_vblank_admissable(struct dc *dc, struct dc_state *context, int
 
 				subvp_disallow |= disallow_subvp_in_active_plus_blank(pipe);
 				refresh_rate = (pipe->stream->timing.pix_clk_100hz * (uint64_t)100 +
-					pipe->stream->timing.v_total * pipe->stream->timing.h_total - (uint64_t)1);
+					pipe->stream->timing.v_total * (unsigned long long)pipe->stream->timing.h_total - (uint64_t)1);
 				refresh_rate = div_u64(refresh_rate, pipe->stream->timing.v_total);
 				refresh_rate = div_u64(refresh_rate, pipe->stream->timing.h_total);
 			}