drm/amd/display: Initialize get_bytes_per_element's default to 1

Variables, used as denominators and maybe not assigned to other values,
should not be 0. bytes_per_element_y & bytes_per_element_c are
initialized by get_bytes_per_element() which should never return 0.

This fixes 10 DIVIDE_BY_ZERO issues reported by Coverity.
Signed-off-by: Alex Hung <alex.hung@amd.com>
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@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/dml/dcn20/display_rq_dlg_calc_20v2.c

@@ -78,7 +78,7 @@ static void calculate_ttu_cursor(struct display_mode_lib *mode_lib,
 
 static unsigned int get_bytes_per_element(enum source_format_class source_format, bool is_chroma)
 {
-	unsigned int ret_val = 0;
+	unsigned int ret_val = 1;
 
 	if (source_format == dm_444_16) {
 		if (!is_chroma)

drivers/gpu/drm/amd/display/dc/dml/dcn21/display_rq_dlg_calc_21.c

@@ -53,7 +53,7 @@ static void calculate_ttu_cursor(
 
 static unsigned int get_bytes_per_element(enum source_format_class source_format, bool is_chroma)
 {
-	unsigned int ret_val = 0;
+	unsigned int ret_val = 1;
 
 	if (source_format == dm_444_16) {
 		if (!is_chroma)