Blackfin arch: add note about newer ezkits using PB4 for AD7877 instead of PJ11

Signed-off-by: NMike Frysinger <vapier.adi@gmail.com>
Signed-off-by: NBryan Wu <cooloney@kernel.org>

arch/blackfin/mach-bf548/boards/ezkit.c

@@ -559,7 +559,7 @@ static struct spi_board_info bfin_spi_board_info[] __initdata = {
 {
 	.modalias		= "ad7877",
 	.platform_data		= &bfin_ad7877_ts_info,
-	.irq			= IRQ_PJ11,
+	.irq			= IRQ_PJ11,	/* newer boards (Rev 1.4+) use IRQ_PB4 */
 	.max_speed_hz		= 12500000,     /* max spi clock (SCK) speed in HZ */
 	.bus_num		= 0,
 	.chip_select  		= 2,