[SERIAL] Remove wrong asm/serial.h inclusions

asm/serial.h is supposed to contain the definitions for the architecture
specific 8250 ports for the 8250 driver.  It may also define BASE_BAUD,
but this is the base baud for the architecture specific ports _only_.

Therefore, nothing other than the 8250 driver should be including this
header file.  In order to move towards this goal, here is a patch which
removes some of the more obvious incorrect includes of the file.

Acked-by: Paul Fulghum <paulkf@microgate.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>