ARM: spear: move all files to mach-spear

There are no conflicting files between the three mach-spear* directories
and plat-spear any more, so we can now move all file to a common
mach-spear directory.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>