patch 9.0.0355: check for uppercase char in autoload name is wrong

Problem:    Check for uppercase char in autoload name is wrong, it checks the
            name of the script.
Solution:   Remove the check. (closes #11031)

src/testdir/test_let.vim

@@ -8,6 +8,10 @@ func Test_let()
   let Test104#numvar = function('tr')
   call assert_equal("function('tr')", string(Test104#numvar))
 
+  let foo#tr = function('tr')
+  call assert_equal("function('tr')", string(foo#tr))
+  unlet foo#tr
+
   let a = 1
   let b = 2