Fix resource leaks identified by cppcheck

* Where possible rearrange error checks to avoid branching
* Otherwise add missing `fclose`, `close`, `px4_close` calls before return

src/systemcmds/sd_bench/sd_bench.c

@@ -118,6 +118,11 @@ sd_bench_main(int argc, char *argv[])
 		}
 	}
 
+	if (block_size <= 0 || num_runs <= 0) {
+		PX4_ERR("invalid argument");
+		return -1;
+	}
+
 	int bench_fd = open(BENCHMARK_FILE, O_CREAT | O_WRONLY | O_TRUNC, PX4_O_MODE_666);
 
 	if (bench_fd < 0) {
@@ -125,16 +130,12 @@ sd_bench_main(int argc, char *argv[])
 		return -1;
 	}
 
-	if (block_size <= 0 || num_runs <= 0) {
-		PX4_ERR("invalid argument");
-		return -1;
-	}
-
 	//create some data block
 	uint8_t *block = (uint8_t *)malloc(block_size);
 
 	if (!block) {
 		PX4_ERR("Failed to allocate memory block");
+		close(bench_fd);
 		return -1;
 	}