The serial layer is restructured to allow less code duplication (and
hence bug duplication) across various serial drivers.  Since ARM adds
six extra serial drivers, maintaining six copies of serial.c was not
my idea of fun.

Therefore, we've ended up with a core serial driver, which knows about
the interactions with the tty layer, and low-level hardware drivers,
which know all about the hardware.  The interface between the two is
described in "Documentation/serial/driver".

This patch completely removes the old serial.c driver and its associated
configuration options, as you requested at KS2002.  We keep a certain
amount of configuration compatibility with the per-architecture serial.h
file for the moment; this *will* be killed in the next round of patches.
The biggest user of this is x86, and since I don't have an x86 box to
test this stuff on, I think the changes are best kept separate.