arm64: traps: Don't print stack or raw PC/LR values in backtraces

Printing raw pointer values in backtraces has potential security
implications and are of questionable value anyway.

This patch follows x86's lead and removes the "Exception stack:" dump
from kernel backtraces, as well as converting PC/LR values to symbols
such as "sysrq_handle_crash+0x20/0x30".

Change-Id: I417aa84c4314b9f53aaeb7f9bd0051f20373f884
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-commit: a25ffd3a6302a67814280274d8f1aa4ae2ea4b59
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>