ARM: omap1: move some headers to include/linux/soc

There are three remaining header files that are used by omap1
specific device drivers:

- mach/soc.h provides cpu_is_omapXXX abstractions
- mach/hardware.h provides omap_read/omap_write functions
  and physical addresses
- mach/mux.h provides an omap specific pinctrl abstraction

This is generally not how we do platform abstractions today,
and it would be good to completely get rid of these in favor
of passing information through platform devices and the pinctrl
subsystem.

However, given that nobody is working on that, just move it
one step forward by splitting out the header files that are
used by drivers today from the machine headers that are only
used internally.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>