Add multi chip support to the FSL-UPM driver

This patch adds support for multi-chip NAND devices to the FSL-UPM
driver. The "dev_ready" callback of the "struct fsl_upm_nand" is now
called with the argument "chip_nr" to allow testing the proper chip
select line. The NAND support of the MPC8360ERDK is updated as well.
No other boards are currently using the FSL UPM driver.

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>