board: ti: Add missing common/Kconfig references

Add missing board/ti/common/Kconfig references for the platforms that
missed it. The intent is for the common Kconfig to be usable across TI
reference boards as required.

Reported-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
diff --git a/board/ti/panda/Kconfig b/board/ti/panda/Kconfig
index 8f277b6..5912f69 100644
--- a/board/ti/panda/Kconfig
+++ b/board/ti/panda/Kconfig
@@ -9,4 +9,6 @@
 config SYS_CONFIG_NAME
 	default "omap4_panda"
 
+source "board/ti/common/Kconfig"
+
 endif