Added support for 8250-class UARTs in HV Sistemas H8606 board,
modification in 8250.c driver for correct compilation with Blackfin

Besides, I think that there is more people using 8250-class UARTs
with a different hardware than the H8606 board. This code can be shared
by them.
Signed-off-by: NJavier Herrero <jherrero@hvsistemas.es>
Acked-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NBryan Wu <cooloney@kernel.org>