scripts: zep2newt: remove unused argument

The --off argument is unused; delete it.

Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
diff --git a/scripts/zep2newt.py b/scripts/zep2newt.py
index 37cff39..efa4b66 100755
--- a/scripts/zep2newt.py
+++ b/scripts/zep2newt.py
@@ -16,8 +16,7 @@
 DEBUG = False
 
 def get_args():
-    parser = ArgumentParser(description='Script to create images on a format \
-                            that Mynewts bootloader expects')
+    parser = ArgumentParser(description='Convert Zephyr binaries to mcuboot format')
 
     parser.add_argument('--bin', required=True, dest='binary_file', \
                         help='Name of *.bin file (input)')
@@ -33,11 +32,6 @@
                         default='SHA256', \
                         help='Type of signature <SHA256|RSA|EC>')
 
-    parser.add_argument('--off', required=False, dest='flash_offs_addr', \
-                        default='0x08020000', \
-                        help='Offset for the binary in flash (at what address \
-                        should it be flashed?)')
-
     parser.add_argument('--word-size', required=False, dest='word_size',
             default=1,
             help='Writable size of flash device (1, 2, 4, or 8)')