firmware: remove computone driver firmware and documentation

The only Computone support left in the kernel is in
drivers/tty/serial/8250/8250_pci.c.  CONFIG_COMPUTONE is no longer a valid
option.  Therefore, remove firmware, documentation, and the last vestiges
of this driver.

Cc: Rob Landley <rob@landley.net>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>