[Hexagon] Fix lowering of formal arguments of type i1

[Hexagon] Fix lowering of formal arguments of type i1

On Hexagon, values of type i1 are passed in registers of type i32,
even though i1 is not a legal value for these registers. This is a
special case and needs special handling to maintain consistency of
the lowering information.

This fixes PR32089.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296645 91177308-0d34-0410-b5e6-96231b3b80d8