fsl_elbc_nand: redirect the pointer of bbt pattern to RAM

fsl_elbc_nand: redirect the pointer of bbt pattern to RAM

The bbt descriptors contains the pointer to the bbt pattern which
are statically initialized memory struct. When relocated to RAM,
these pointers will continue point to NOR flash(or L2 SRAM, or
other boot device). If the contents of NOR flash changed or L2
SRAM disabled, it'll hang the system.

Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>