ARM: OMAP2+: Remove legacy i2c.c platform init code

We can now initialize I2C for mach-omap2 using device tree. And we
can move the remaining code in plat-omap/i2c.c into mach-omap1/i2c.c.

Note that we cannot remove some of the I2C bus reset functions
as they are being used by hwmod code.

Signed-off-by: Tony Lindgren <tony@atomide.com>