Blackfin Serial Driver: fix baudrate for early_printk

Since we already setup the early console UART in
arch/blackfin/kernel/early_printk.c, and common functions which are
enabled from the .setup will override the proper settings later, don't
fill in these structures.  Otherwise we get mangled baudrate settings when
using early_printk.

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>