cmd: part: use MAX_SEARCH_PARTITIONS for part search

Use Macro instead of hard code.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

cmd/part.c

@@ -90,7 +90,7 @@ static int do_part_list(int argc, char * const argv[])
 		char str[512] = { '\0', };
 		disk_partition_t info;
 
-		for (p = 1; p < 128; p++) {
+		for (p = 1; p < MAX_SEARCH_PARTITIONS; p++) {
 			char t[5];
 			int r = part_get_info(desc, p, &info);