[ARM] arm32ve: No need pack struct arm_priv

We only need to pack structures that are directly accessed
by HW or accessed from assembly code hence remove packing
attribute for struct arm_priv.

We also reorganize struct arm_priv_cp15 and struct arm_priv_vfp
to ensure that all 'u64' fields are at 64bit aligned offset.

Signed-off-by: Anup Patel <anup@brainfault.org>