re-enable the currently disable ppc tests once qemu is fixed

[lu-zero]

here the upstream issue.

[sayantn]

The qemu issue seems to have been resolved, and the PPC64LE target is all good now, but the PPC64 target still (consistently) fails the vec_lde tests - but only with -C target-feature=+vsx

[sayantn]

---- core_arch::powerpc::altivec::tests::test_vec_lde_u16 stdout ----
thread 'core_arch::powerpc::altivec::tests::test_vec_lde_u16' panicked at crates/core_arch/src/powerpc/altivec.rs:4802:13:
assertion `left == right` failed
  left: 0
 right: 111
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- core_arch::powerpc::altivec::tests::test_vec_lde_u32 stdout ----
thread 'core_arch::powerpc::altivec::tests::test_vec_lde_u32' panicked at crates/core_arch/src/powerpc/altivec.rs:4811:13:
assertion `left == right` failed
  left: 0
 right: 7303781

(with qemu-ppc64 version 8.2.2 in Ubuntu 24.04, CPU is set to Power10