arm64: Remove the aux_context structure

This patch removes the aux_context structure (and the containing file)
to allow the placement of the _aarch64_ctx end magic based on the
context stored on the signal stack.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: 0e0276d1e1dd063cd14ce377707970d0417a0792
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>