ARM: 7878/1: nommu: Implement dummy early_paging_init()

No-MMU configurations currenty fail to build because they are missing
the early_paging_init() symbol.

Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>