powerpc: Revert CHRP boot wrapper to real-base = 12MB on 32-bit

Commit 9b09c6d909 ("powerpc: Change the
default link address for pSeries zImage kernels") changed the
real-base value in the CHRP note added by addnote to the zImage from
12MB to 32MB.  It turns out that this causes unnecessary extra reboots
on old 32-bit CHRP machines.  This therefore adds a -r flag to addnote
to allow us to specify what real-base value it should put in the CHRP
note, and adjusts the wrapper script to pass -r c00000 to addnote when
making a zImage for a CHRP machine.  Also, CHRP machines ignore the
RPA note, so we don't need to arrange for it to be the same as the
kernel's.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/boot/wrapper

@@ -306,11 +306,14 @@ fi
 
 # post-processing needed for some platforms
 case "$platform" in
-pseries|chrp)
+pseries)
     ${CROSS}objcopy -O binary -j .fakeelf "$kernel" "$ofile".rpanote
     $objbin/addnote "$ofile" "$ofile".rpanote
     rm -r "$ofile".rpanote
     ;;
+chrp)
+    $objbin/addnote -r c00000 "$ofile"
+    ;;
 coff)
     ${CROSS}objcopy -O aixcoff-rs6000 --set-start "$entry" "$ofile"
     $objbin/hack-coff "$ofile"