ARM: OMAP: Split plat-omap/i2c.c into mach-omap1 and mach-omap2

There's no need to keep the device related things in the
common i2c.c as omap2+ is using hwmod. Split the code to
mach-omap1 and mach-omap2 parts and only leave common
code to plat-omap/i2c.c.

Note that as omap1 only has one i2c controller, we can
now remove the old device related macros.

Reviewed-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>