ls1046aqds: Bypass xfi port fixup for KR mode

u-boot makes a fixup for LS1046AQDS board to setup the properties
'fixed-link' and 'phy-connection-type' to 'xgmii' but in case of
backplane mode this fixup is not correct because it causes the KR link
to fail and so it must be bypassed in order to keep the link in KR
mode as it is defined in DTS.

Signed-off-by: Florinel Iordache <florinel.iordache@nxp.com>
[YS: Fix compiling warning]
Reviewed-by: York Sun <york.sun@nxp.com>