This adds device tree support for the U300 timer, by making
the memory base offset and IRQ dynamically assigned, then
optionally looking them up from the device tree.

Since the timer needs to be registered before any platform
devices are created, we will go into the device tree and look
up the "/timer@c0014000" node and read our base address and
IRQ from there.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Now that the only field in struct sys_timer is .init, delete the struct,
and replace the machine descriptor .timer field with the initialization
function itself.

This will enable moving timer drivers into drivers/clocksource without
having to place a public prototype of each struct sys_timer object into
include/linux; the intent is to create a single of_clocksource_init()
function that determines which timer driver to initialize by scanning
the device dtree, much like the proposed irqchip_init() at:
http://www.spinics.net/lists/arm-kernel/msg203686.html

Includes mach-omap2 fixes from Igor Grinberg.
Tested-by: NRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: NStephen Warren <swarren@nvidia.com>

This gets rid of the separate u300.c file in mach-u300 since
it can just as well live right in core.c, then we also get
rid of the broadcasted <mach/platform.h> file that is not
helping anyone. Put the interface to the system timer into
a separate header.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>