[XCore] Fix call of absolute address.

Previously for:

tail call void inttoptr (i64 65536 to void ()*)() nounwind

We would emit:

bl 65536

The immediate operand of the bl instruction is a relative offset so it is
wrong to use the absolute address here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202860 91177308-0d34-0410-b5e6-96231b3b80d8