tbs2910: remove deprecated CONFIG_SYS_EXTRA_OPTIONS

move options from CONFIG_SYS_EXTRA_OPTIONS to board specific Kconfig

Signed-off-by: Soeren Moch <smoch@web.de>
diff --git a/board/tbs/tbs2910/Kconfig b/board/tbs/tbs2910/Kconfig
index 84b243e..a795837 100644
--- a/board/tbs/tbs2910/Kconfig
+++ b/board/tbs/tbs2910/Kconfig
@@ -12,4 +12,10 @@
 config SYS_CONFIG_NAME
 	default "tbs2910"
 
+config MX6Q
+	default y
+
+config IMX_CONFIG
+	default "board/boundary/nitrogen6x/nitrogen6q2g.cfg"
+
 endif
diff --git a/configs/tbs2910_defconfig b/configs/tbs2910_defconfig
index 5dca230..822aec3 100644
--- a/configs/tbs2910_defconfig
+++ b/configs/tbs2910_defconfig
@@ -1,7 +1,6 @@
 CONFIG_ARM=y
 CONFIG_ARCH_MX6=y
 CONFIG_TARGET_TBS2910=y
-CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/boundary/nitrogen6x/nitrogen6q2g.cfg,MX6Q"
 # CONFIG_CMD_IMLS is not set
 # CONFIG_CMD_FLASH is not set
 CONFIG_DM=y