ARM: 7751/1: zImage: don't overwrite ourself with a page table

When zImage is loaded into RAM at a low address but TEXT_OFFSET
is set higher, we risk overwriting ourself with the page table
needed to turn on the cache as it is located relative to the relocation
address.  Let's defer the cache setup after relocation in that case.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reported-by: Stephen Boyd <sboyd@codeurora.org>
Tested-by: Stephen Boyd <sboyd@codeurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>