powerpc: fix compile error with 85xx/p1022_ds.c

Current linux-next compiled with mpc85xx_defconfig causes this:
 arch/powerpc/platforms/85xx/p1022_ds.c:341:14: error: 'udbg_progress' undeclared here (not in a function)

Add include to fix this.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>