ARM: ux500: core U9540 support

ARM: ux500: core U9540 support

This adds support for the U9540 variant of the U8500 series. This
is an application processor without internal modem. This is the
most basic part with ASIC ID, CPU-related fixes, IRQ list, register
ranges, timer, UART, and L2 cache setup. This is based on a patch
by Michel Jaouen which was rewritten to fit with the latest 3.3
kernel.

ChangeLog v1->v2: deleted the irqs-db9540.h file since we expect to
  migrate to using Device Tree for getting the IRQs to devices.
ChangeLog v2->v3: introduced a fixed virtual offset for the ROM
  as suggested by Arnd Bergmann.

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sebastien Pasdeloup <sebastien.pasdeloup-nonst@stericsson.com>
Signed-off-by: Michel Jaouen <michel.jaouen@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>