Blackfin arch: Fix bug - set corret SSEL and IRQ to enable AD7877 on BF527

AD7877 use SSEL_2 (P9.9) and IRQ_PF8 (P9.14) on BF527

 - populating JP3 to enable STAMP
 - disable SW11.2 to disconnect SSEL_2/PF12 from Rotary NAND
 - disable SW18.1 to disconnect SSEL_2 from MAX1233 touchscreen chip

Signed-off-by: Bryan Wu <cooloney@kernel.org>