arm64: ftrace: Modernise annotation of return_to_handler

In an effort to clarify and simplify the annotation of assembly
functions new macros have been introduced. These replace ENTRY and
ENDPROC with two different annotations for normal functions and those
with unusual calling conventions.

return_to_handler does entertaining things with LR so doesn't follow the
usual C conventions and should therefore be annotated as code rather than
a function.

Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>