ARM: p2v: factor out shared loop processing

The ARM and Thumb2 versions of the p2v patching loop have some overlap
at the end of the loop, so factor that out. As numeric labels are not
required to be unique, and may therefore be ambiguous, use named local
labels for the start and end of the loop instead.

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>