board: colibri-imx6ull: Do not leave variant variable unset

Toradex uses the variable variant to distinguish between modules with
eMMC, NAND with wifi and NAND without wifi.
This variable is set on every boot. Set this variable also if we have a
NAND module without wifi to prevent issues.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
diff --git a/board/toradex/colibri-imx6ull/colibri-imx6ull.c b/board/toradex/colibri-imx6ull/colibri-imx6ull.c
index 02ab588..3244184 100644
--- a/board/toradex/colibri-imx6ull/colibri-imx6ull.c
+++ b/board/toradex/colibri-imx6ull/colibri-imx6ull.c
@@ -172,10 +172,14 @@
 	} else {
 		if (is_emmc)
 			env_set("variant", "-emmc");
+		else
+			env_set("variant", "");
 	}
 #else
 	if (is_emmc)
 		env_set("variant", "-emmc");
+	else
+		env_set("variant", "");
 #endif
 
 	/*