drm/amd/display: Cast int to float before division

[Why]:
Some inputs to dml_ceil have it dividied by int which causes a
truncation. This loss of precision means the ceil function becomes
redundant and does not round up.

[How]:
Cast parameter to float before division.

Signed-off-by: Sung Lee <[e-mail]>
Reviewed-by: Dmytro Laktyushkin <[e-mail]>
Acked-by: Rodrigo Siqueira <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/dml/dcn21/display_mode_vba_21.c

···
 						* PixelPTEReqHeightY[k];
 			}
 			dpte_groups_per_row_luma_ub = dml_ceil(
-					dpte_row_width_luma_ub[k] / dpte_group_width_luma,
+					(float) dpte_row_width_luma_ub[k] / dpte_group_width_luma,
 					1);
 			time_per_pte_group_nom_luma[k] = DST_Y_PER_PTE_ROW_NOM_L[k] * HTotal[k]
 					/ PixelClock[k] / dpte_groups_per_row_luma_ub;
···
 							* PixelPTEReqHeightC[k];
 				}
 				dpte_groups_per_row_chroma_ub = dml_ceil(
-						dpte_row_width_chroma_ub[k]
+						(float) dpte_row_width_chroma_ub[k]
 								/ dpte_group_width_chroma,
 						1);
 				time_per_pte_group_nom_chroma[k] = DST_Y_PER_PTE_ROW_NOM_C[k]