tools: mkimport.sh: Add support relative file path

Summary:
- mkimport.sh only accepted absolute file path
- This commit adds support relative file path

Impact:
- None

Testing:
- Build (mkimport, make import) with sama5d4-ek:knsh

Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

tools/mkimport.sh

@@ -35,7 +35,7 @@ while [ ! -z "$1" ]; do
 			;;
 		-x )
 			shift
-			EXPORT=$1
+			EXPORT=$(realpath $1)
 			;;
 		-z )
 			TGZ=y