ARM: 5625/1: fix hard coded 4K resource size in amba bus detection

This patch modifies the amba bus detection logic in the kernel
to detect the AMBA devices using the calculated resource
size information rather than the hard coded 4K size.

It also calculates the resource size when request mem region
and release mem region.

Signed-off-by: Leo Chen <leochen@broadcom.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>