Making SMP depend on (huge list of MACH_ and ARCH_ configs) is
bothersome to maintain and likely to lead to merge conflicts.

This patch moves the knowledge of which platforms are SMP-capable
to the individual machines. To enable this, a new HAVE_SMP config
option is introduced to allow machines to indicate that they can
run in a SMP configuration.

Signed-off-by: Dave Martin
Acked-by: Linus Walleij
(for nomadik, ux500)
Acked-by: Tony Lindgren
(for omap)
Acked-by: Kukjin Kim
(for exynos)
Acked-by: Sascha Hauer
(for imx)
Acked-by: Olof Johansson
(for tegra)