soc/fsl/qe: get rid of immrbar_virt_to_phys()

immrbar_virt_to_phys() is not used anymore

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Li Yang <pku.leo@gmail.com>
Signed-off-by: Scott Wood <oss@buserror.net>