[AVR] Fix the 'call.ll' CodeGen test

Commit r343851 changed the format of the generated instructions.

An unnecessary load has been removed. Previously, a value would be moved
from r24 into a temporary register just to be copied into r30 before the
indirect call. Now, codegen immediately loads r24 into r30, saving a
MOVW instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344111 91177308-0d34-0410-b5e6-96231b3b80d8