charger: screen blank on disconnect and 0% not displayed

Bug: 74771887
Test: m -j succeeded and confirm offmode charge UI behavior
Change-Id: I8c97230f6c1e32ac9949601a86added79a3ead82
Signed-off-by: kentsou <kentsou@google.com>
diff --git a/healthd/healthd_draw.cpp b/healthd/healthd_draw.cpp
index 30f2cf3..706dc80 100644
--- a/healthd/healthd_draw.cpp
+++ b/healthd/healthd_draw.cpp
@@ -173,7 +173,7 @@
         cur_level = 100;
     }
 
-    if (cur_level <= 0) return;
+    if (cur_level < 0) return;
 
     const animation::text_field& field = anim->text_percent;
     if (field.font == nullptr || field.font->char_width == 0 || field.font->char_height == 0) {