serial: sh-sci: Bring oversized error handlers out of line.

Presently much of the error handling paths are inlined, stemming from a
time when they were much smaller. This simply brings them out of line and
leaves it up to the compiler. Given that some of these now contain nested
loops, it's pretty hard to justify the inlining regardless of the
footprint.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>