arm64: stacktrace: rename unwind_next_common() -> unwind_next_frame_record()

arm64: stacktrace: rename unwind_next_common() -> unwind_next_frame_record()

The unwind_next_common() function unwinds a single frame record. There
are other unwind steps (e.g. unwinding through trampolines) which are
handled in the regular kernel unwinder, and in future there may be other
common unwind helpers.

Clarify the purpose of unwind_next_common() by renaming it to
unwind_next_frame_record(). At the same time, add commentary, and delete
the redundant comment at the top of asm/stacktrace/common.h.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220901130646.1316937-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>