ARM: OMAP2+: Cleanup omap_i2c_dev_attr usage

The omap_i2c_dev_attr data was used to supply instance-specific
data for legacy non-DT devices. The I2C legacy device support has
been cleaned up in commit 65fa3e71 ("ARM: OMAP2+: Remove legacy
i2c.c platform init code") and this data is therefore no longer
needed. So, cleanup the structure and all the associated data in
various hwmod data files.

The i2c-omap.h header is still needed because of the need for
various OMAP_I2C_IP_VERSION_x macros.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>