Skip qtserialport in Android builds

Qtserialport won't work without rooted Androids anyways.

Task-number: QTBUG-69727
Change-Id: I9a14a8e880d8e238a7f75ce12ca805c5af476407
Reviewed-by: BogDan Vatra <bogdan@kdab.com>

qtserialport.pro

@@ -7,6 +7,7 @@ requires(!integrity)
 requires(!vxworks)
 requires(!winrt)
 requires(!uikit)
+requires(!android)
 
 load(configure)
 qtCompileTest(ntddmodm)