powerpc: allow ioremap within reserved memory regions

powerpc: allow ioremap within reserved memory regions

Add a flag to let a platform ioremap memory regions marked as reserved.

This flag will be used later by the Nintendo Wii support code to allow
ioremapping the I/O region sitting between MEM1 and MEM2 and marked
as reserved RAM in the patch "wii: use both mem1 and mem2 as ram".

This will no longer be needed when proper discontig memory support
for 32-bit PowerPC is added to the kernel.

Signed-off-by: Albert Herranz <[email protected]>
Acked-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Grant Likely <[email protected]>