[Thumb2] Upgrade intrinsic upgrading code

Enabling opaque pointers has changed the mangled names of these two ARM
intrinsics:

`arm.mve.vldr.gather.offset.predicated.v2i64.p0i64.v2i64.v4i1`
`arm.mve.vstr.scatter.offset.predicated.p0i64.v2i64.v2i64.v4i1`

They are now spelled as:

`arm.mve.vldr.gather.offset.predicated.v2i64.p0.v2i64.v4i1`
`arm.mve.vstr.scatter.offset.predicated.p0.v2i64.v2i64.v4i1`

Upgrade intrinsic upgrading code to account for the change in names.

Differential Revision: https://reviews.llvm.org/D142900