avr32: Use correct config symbol in atstk1004 board code

CONFIG_BOARD_ATSTK1002_SW2_CUSTOM should be
CONFIG_BOARD_ATSTK100X_SW2_CUSTOM.

Spotted by Robert P. J. Day.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
1 file changed