ARM: 7637/1: memory: use SZ_ constants for defining the virtual memory layout

Parts of the virtual memory layout (mainly the modules area) are
described using open-coded immediate values.

Use the SZ_ definitions from linux/sizes.h instead to make the code
clearer.

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>