[ARM] 5389/1: Make sure the pmd entries are visible by the secondary CPU

The __cpu_up() function in arch/arm/kernel/smp.c sets the pmd entries
without flushing or cleaning them.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>