ARM: 7646/1: mm: use static_vm for managing static mapped areas

A static mapped area is ARM-specific, so it is better not to use
generic vmalloc data structure, that is, vmlist and vmlist_lock
for managing static mapped area. And it causes some needless overhead and
reducing this overhead is better idea.

Now, we have newly introduced static_vm infrastructure.
With it, we don't need to iterate all mapped areas. Instead, we just
iterate static mapped areas. It helps to reduce an overhead of finding
matched area. And architecture dependency on vmalloc layer is removed,
so it will help to maintainability for vmalloc layer.

Reviewed-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>