ARM: 7772/1: Fix missing flush_kernel_dcache_page() for noMMU

commit 63384fd0b1509acf522a8a8fcede09087eedb7df upstream.

Commit 1bc3974 (ARM: 7755/1: handle user space mapped pages in
flush_kernel_dcache_page) moved the implementation of
flush_kernel_dcache_page() into mm/flush.c but did not implement it
on noMMU ARM.

Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>