This fixes a crash when using --trace-ic on Arm64 debug. For a given return
address, the assembler's `target_address_from_return_address()` method will
displace it to give you the call-site address. However, this is fragile because
it needs to decode the instruction stream to distinguish between different call
sequences. So it triggered an assertion on Arm64 because we now use BL for
builtin to buitin calls.

We only use this when tracing IC states to detect if the caller is a deoptimized
function. But to do this it doesn't matter if the address we have is the return
or the call-site address. So we can just remove the need for the fragile
Assembler method.

As a drive-by, also remove `return_address_from_call_start()` which was doing
the opposite and was unused.

Change-Id: I5988d17eadd1652ed85d662e62bc4c579665dd31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1594566
Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61337}