i2c: omap: abolish variable name confusion

struct device pointers are usually called
dev. Calling our struct omap_i2c_dev pointers
also dev has caused enough confusion.

This is the result of a few simple sed rules
to convert all struct omap_i2c_dev pointers
to be called omap instead.
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>