fix: Fix the ESP USB CDC ACM port read return value

This makes sure that we correctly indicate timeout instead of
unrecoverable failure for when not all data requested is read and fixes
an issue with initial SYNC packet connection, where there would be no
retries.

Closes #117

Author: DNedic

port/esp32_usb_cdc_acm_port.c

@@ -156,7 +156,7 @@ esp_loader_error_t loader_port_read(uint8_t *data, const uint16_t size, const ui
 #endif
         return ESP_LOADER_SUCCESS;
     } else {
-        return ESP_LOADER_ERROR_FAIL;
+        return ESP_LOADER_ERROR_TIMEOUT;
     }
 }