powerpc/powermac: Remove empty function note_scsi_host()

note_scsi_host() has been an empty function since
commit 6ee0d9f7 ("[POWERPC] Remove unused old code
from powermac setup code").

Remove it.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/26f8b72a4276c0bd8ed63860c7316f6361c351b4.1655978907.git.christophe.leroy@csgroup.eu