8250: remove a few inlines of dubious value

Remove some inlines from various functions that are called once, are too
big to inline, or are called only from slow path code.  This saves around
300 bytes of code for me.

Signed-off-by: Will Newton <will.newton@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>