[PATCH] powerpc: clean up iommu.h a bit

There was a function declared for CONFIG_PSERIES which no longer exists
and the two function declarations for CONFIG_ISERIES have been moved
into an include file in platforms/iseries since they are defined and
used only there.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>