GCC doesn't accept 'lr' in inline assembly, specifically for the
list of clobbered registers. Change all uses to 'x30', for
consistency.

Bug: v8:10026
Change-Id: I5654fee4ca398dfdd99c34d09fc5294d169a9bd8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3693701Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Cr-Commit-Position: refs/heads/main@{#80980}