[mlir][AMDGPU] Avoid verifier crash in DPPOp on vector operand types (#178887)

### whats the problem 
mlir-opt could crash while verifying amdgpu.dpp when its operands had
vector
types, such as ARM SME tile vectors produced by arm_sme.get_tile.
The crash occurred during IR verification, before any lowering or passes
ran.

### why it happens 
DPPOp::verify() called Type::getIntOrFloatBitWidth() on the operand
type.
When the operand was a VectorType, this hit an assertion because only
scalar
integer and float types have a bitwidth.

### whats the fix 
Query the bitwidth on the element type using getElementTypeOrSelf()
instead of
the container type.
Add a regression test to ensure amdgpu.dpp verification no longer
asserts on
vector operand types.

Fixes #178128

0 files changed, 0 insertions, 0 deletions