NXP: Introduce board/freescale/common/Kconfig and migrate CHAIN_OF_TRUST

Introduce board/freescale/common/Kconfig so that we have a single place
for CONFIG options that are shared between ARM and PowerPC NXP platforms.

Cc: York Sun <york.sun@nxp.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: York Sun <york.sun@nxp.com>
diff --git a/board/freescale/ls1043ardb/Kconfig b/board/freescale/ls1043ardb/Kconfig
index 80203a4..1bab7ca 100644
--- a/board/freescale/ls1043ardb/Kconfig
+++ b/board/freescale/ls1043ardb/Kconfig
@@ -22,4 +22,6 @@
 	  If enabled, please also define the value for ARMV8_SECURE_BASE,
 	  for LS1043ARDB, it could be some address in OCRAM.
 
+source "board/freescale/common/Kconfig"
+
 endif