ARM: 7090/1: CACHE-L2X0: filter start address can be 0 and is often 0

this patch fixes the error in Rob Herring's
ARM: 7009/1: l2x0: Add OF based initialization
http://www.spinics.net/lists/arm-kernel/msg131123.html
it has been in rmk/for-next with commit 41c86ff5b

Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Acked-by: Rob Herring <robherring2@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>