ARM: dts: OMAP3+: Add i2c aliases

Currently, on OMAP5, i2c1 and i2c5 defer probe due to pinctrl
dependencies. This changes the i2c ID each bus is registered with in
i2c-dev interface. As a result of this, many userspace tools break and
there is no consistent manner to fix the same if the i2c dev interface
have no consistent numbering.

Since this could happen for other OMAP derivatives, provide i2c alias
for all OMAP3+ SoCs to allow ordering the i2c devices correctly.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>