Rework and add some new APIs to the fsl_corenet_serdes code for use by
erratum and drivers.

* Rename serdes_get_bank() to serdes_get_bank_by_lane()
* Add serdes_get_first_lane returns which SERDES lane is used by device
Signed-off-by: NEmil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: NTimur Tabi <timur@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>