arm64: disable ARM64_ERRATUM_843419 for clang LTO

CONFIG_LTO_CLANG depends on GNU gold, which can generate ADR_PREL_PG_HI21
relocations with --fix-cortex-a53-843419, even when -code-model=large has
been passed to LLVMgold.

Since ARM64_ERRATUM_843419 disables kernel support for these relocations,
disable the erratum when LTO is used.

Bug: 67506682
Change-Id: I5d419cae432a26af5b6eff362b869639c64c6fb3
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>