lpc32xx: devkit3250: update of board configuration

lpc32xx: devkit3250: update of board configuration

This change adds more peripherals to Timll DevKit3250 board, namely
MAC and SMSC phy, SLC NAND, GPIO, SPI and I2C.

Also the default serial console is changed to UART5, added an option
to pass device tree blob by means of bootm, predefined environment
variables are slightly extended and reserved space on NAND to store
user defined U-boot environment.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>