serial: bfin_5xx: fix building as module when early printk is enabled

serial: bfin_5xx: fix building as module when early printk is enabled

commit 607c268ef9a4675287e77f732071e426e62c2d86 upstream.

Since early printk only makes sense/works when the serial driver is built
into the kernel, disable the option for this driver when it is going to be
built as a module.  Otherwise we get build failures due to the ifdef
handling.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>