arm: dts: ls1088aqds: add CONFIG_MULTI_DTB_FIT support

arm: dts: ls1088aqds: add CONFIG_MULTI_DTB_FIT support

Add support for selecting the appropriate DTS file depending on the
SERDES protocol used. The fsl-ls2088a-qds DTS will be used by default if
there isn't a DTS file specifically made for the current SERDES
protocol.

This patch adds support for the on-board ports (DPMAC 1,2 and 4,5) found
on the SERDES protocols 21(0x15) and 29(0x1d) for SD#1.

On the LS1088AQDS board EMDIO1 is used with two onboard RGMII PHYs
(Realtek RTL8211FD-CG), as well as 2 input/output connectors for
mezzanine cards. Configuration signals from the Qixis FPGA control the
routing of the external MDIOs.

Register 0x54 of the Qixis FPGA controls the routing of the EMDIO1 one
of the 2 IO slots. As a consequence, a new node is added to
describe register 0x54 as a MDIO mux controlled with child nodes
describing all the IO slots as MDIO buses.

Also, in case CONFIG_DM_ETH and CONFIG_MULTI_DTB_FIT are enabled
implement the board_fit_config_name_match() function in order to choose
the appropriate DTS.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>