board: fsl: ls1028a: free up arch_misc_init

Currently LS1028A board code uses arch_misc_init to set up the board mux
on QDS.  Move this code to misc_init_r.  This is consistent with LS gen 2
and T series SoCs/boards.

Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>