all.sh: keep dd output in non-quiet mode

Since dd prints everything on stderr, both normal status update and actual
errors when they occur, redirecting that to /dev/null is a trade-off that's
acceptable in quiet mode (typically used on a developer's machine and the
developer will re-run in non-quiet mode if anything fails without sufficient
detail in the output), but not that much in non-quiet mode.

For example, if our dd invocation fails because the disk in full on a CI
machine, we want the error to be reported at the time we invoke dd, and not
later when a seemingly unrelated test fails due to an incorrect seedfile.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

tests/scripts/all.sh

@@ -510,10 +510,16 @@ pre_setup_quiet_redirect () {
         redirect_out () {
             "$@"
         }
+        redirect_err () {
+            "$@"
+        }
     else
         redirect_out () {
             "$@" >/dev/null
         }
+        redirect_err () {
+            "$@" 2>/dev/null
+        }
     fi
 }
 
@@ -1925,7 +1931,7 @@ run_component () {
     # Unconditionally create a seedfile that's sufficiently long.
     # Do this before each component, because a previous component may
     # have messed it up or shortened it.
-    dd if=/dev/urandom of=./tests/seedfile bs=64 count=1 >/dev/null 2>&1
+    redirect_err dd if=/dev/urandom of=./tests/seedfile bs=64 count=1
 
     # Run the component code.
     if [ $QUIET -eq 1 ]; then