arm: Fix wrong code with MVE V2DImode loads and stores [PR99960]

arm: Fix wrong code with MVE V2DImode loads and stores [PR99960]

As the PR shows, we currently miscompile V2DImode loads and stores for
MVE.  We're currently using 64-bit loads/stores, but need to be using
128-bit vector loads and stores. Fixed thusly.

Some intrinsics tests were checking that we (incorrectly) used the
64-bit loads/stores: these have been updated.

gcc/ChangeLog:

	PR target/99960
	* config/arm/mve.md (*mve_mov<mode>): Simplify output code. Use
	vldrw.u32 and vstrw.32 for V2D[IF]mode loads and stores.

gcc/testsuite/ChangeLog:

	PR target/99960
	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_s64.c:
	Update now that we're (correctly) using full 128-bit vector
	loads/stores.
	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_u64.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_z_s64.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vldrdq_gather_base_wb_z_u64.c:
	Likewise.
	* gcc.target/arm/mve/intrinsics/vuninitializedq_int.c: Likewise.
	* gcc.target/arm/mve/intrinsics/vuninitializedq_int1.c:
	Likewise.