Adapt to ppc media layout change

Media layout for ppc now looks like media layout on other arches

Signed-off-by: Dinar Valeev <dvaleev@suse.com>
GRUB2 binary got renamed to fit HFS 8.3

We should have grub2 binary compatible with HFS's 8.3 format

Signed-off-by: Dinar Valeev <dvaleev@suse.com>
Merge pull request #319 from k0da/master

Update media builder for PowerPC