ARM: restart: remove the now empty arch_reset()

Remove the now empty arch_reset() from all the mach/system.h includes,
and remove its callsite.  Remove arm_machine_restart() as this function
no longer does anything useful.

For samsung platforms, remove the include of mach/system-reset.h and
plat/system-reset.h from their respective mach/system.h headers as these
just define their arch_reset functions.  As a result, the s3c2410 and
plat-samsung system-reset.h files are no longer referenced, so remove
these files entirely.

Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>