linux-imx

LF-191-2 i2c: introduce xen i2c paravirtualization driver

Add i2c backend frontend support.
The transaction only support one msg each time.
The frontend sends a request to backend, backend use i2c_transfer
to do real transaction to hardware and return the results to frontend.

Now i2cdump/get/set works.
In domu cfg file, use
"vi2c = ['backend=0,be-adapter=5a800000.i2c,addr=0x51;0x44']" to
create a dummy controller in frontend and allowed slaves in backend.

Currently the slave address check not added, it will be supported in
furture patch.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Acked-by: Leonard Crestez <leonard.crestez@nxp.com>