[ARM,MVE] Fix predicate types of some intrinsics

Summary:
Some predicated MVE intrinsics return a vector with element size
different from the input vector element size. In this case the
predicate must type correspond to the output vector type.

The following intrinsics use the incorrect predicate type:
* llvm.arm.mve.mull.int.predicated
* llvm.arm.mve.mull.poly.predicated
* llvm.arm.mve.vshll.imm.predicated

This patch fixes the issue.

Reviewers: simon_tatham, dmgreen, ostannard, MarkMurrayARM

Reviewed By: MarkMurrayARM

Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D74838