[ARM] 5056/1: [AT91] Cleanup YL9200 board file

Cleanup the YL9200 board-support file.

Other things fixed are:
 - Use new-style UART initialization
 - Register all LEDs as gpio_leds.
 - NOR Flash error noted in comments fixed by increasing YL9200_FLASH_SIZE
 - The only I2C device is the AT24C eeprom.
 - Setup of NWAIT pin and programming of SMC controller for the LCD/VGA.
 - Configure touchscreen interrupt pin.

Also adding the board to the KConfig and Makefile.

Signed-off-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>