[ARM] 4850/1: include generic pgtable.h for !CONFIG_MMU case

The nonmmu version of pgtable.h needs to include asm-generic/pgtable.h
as well. It needs to pick up empty definitions of things like
arch_enter_lazy_cpu_mode() to compile cleanly.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>