arm64: remove gratuitious/stray .ltorg stanzas

There are no applicable literals above them.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Remi Denis-Courmont <remi.denis.courmont@huawei.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>