serial: sh-sci: Fix build failure for non-sh architectures.

serial: sh-sci: Fix build failure for non-sh architectures.

This patch fixes a build failure for various arm based defconfigs
[1][2][3] and maybe other architectures/configs.

The build failure was introduced by the sh specific patch [4]
"serial: sh-sci: Add DMA support"
by Guennadi Liakhovetski

Patch against linux-next of 20100309

References:
[1] http://kisskb.ellerman.id.au/kisskb/buildresult/2248992/
[2] http://kisskb.ellerman.id.au/kisskb/buildresult/2248996/
[3] http://kisskb.ellerman.id.au/kisskb/buildresult/2248998/
[4] http://git.kernel.org/?p=linux/kernel/git/sfr/linux-next.git;a=commit;h=73a19e4c0301908ce6346715fd08a74308451f5a

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>