TQM85xx: Fix a couple warnings in TQM8548 build

TQM85xx: Fix a couple warnings in TQM8548 build

The ecm variable in sdram.c was being declared for all 8548, but only
used by specific 8548 boards, so we make that variable require those
specific boards, too

The nand code was using an index "i" into a table, and then re-using "i"
to set addresses for each upm.  However, then it relied on the old value
of i still being there to enable things.  Changed the second "i" to "j"

Signed-off-by: Andy Fleming <afleming@freescale.com>