ARM: 7372/1: ux500: factor out dynamic amba device allocator

This replaces the dynamic device allocator in the ux500 machine
with the common device allocator in the bus code.

Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Cc: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>