NAND FSL elbc: Use virt_to_phys to determine which bank is in use

NAND FSL elbc: Use virt_to_phys to determine which bank is in use

The current code that determines which bank/chipselect is used for a
given NAND instance only worked for 32-bit addresses and assumed
a 1:1 mapping.  This breaks in 36-bit physical configs.

The proper way to handle this is to use the virt_to_phys() and
BR_PHYS_ADDR() routinues to match the 34-bit lbc bus address
with the the virtual address the NAND code uses.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Scott Wood <scottwood@freescale.com>