dm-verity-img.bbclass: set sparse as "never" during initial file copy

This is needed when a verity image is used in conjunction with tools
like a WIC and a bmap file, as avoiding writing "sparse" sectors
can result in errors in the signature verification.

Signed-off-by: Lorenzo Arena <arena.lor@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

classes/dm-verity-img.bbclass

@@ -146,7 +146,7 @@ verity_setup() {
         HASH_OFFSET="--hash-offset="$SIZE
     fi
 
-    cp -a $INPUT $OUTPUT
+    cp -a --sparse=never $INPUT $OUTPUT
 
     SETUP_ARGS=" \
         ${DM_VERITY_SETUP_ARGS} \