[mlir][openacc] Add canonicalization pattern for acc.host_data

Add if condition removal pattern for acc.host_data in a same way as
acc.enter_data, acc.exit_data and acc.update.

The condition is removed from the op if it is a true constant. If
it is a false constant then the region is inlined before the op
and the op is removed.

Reviewed By: vzakhari

Differential Revision: https://reviews.llvm.org/D150480