Blackfin arch: split board selection off into mach subdirs

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/mach-bf548/Kconfig b/arch/blackfin/mach-bf548/Kconfig
index 08d8dc8..d8bd3b49 100644
--- a/arch/blackfin/mach-bf548/Kconfig
+++ b/arch/blackfin/mach-bf548/Kconfig
@@ -1,5 +1,7 @@
 if (BF54x)
 
+source "arch/blackfin/mach-bf548/boards/Kconfig"
+
 menu "BF548 Specific Configuration"
 
 config DEB_DMA_URGENT