cleanup_minimal: remove duplicate trap for temps and mounts

BUG=chromium:1141907
TEST=unit tests and manual signing run
Signed-off-by: George Engelbrecht <engeg@google.com>
BRANCH=none

Change-Id: I0316f464e138dea9e77b2554a3b31250e8b92c07
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2514559
Reviewed-by: Sean McAllister <smcallis@google.com>
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
Commit-Queue: George Engelbrecht <engeg@google.com>
Tested-by: George Engelbrecht <engeg@google.com>
diff --git a/scripts/image_signing/common_minimal.sh b/scripts/image_signing/common_minimal.sh
index 2770b8f..e8f0336 100644
--- a/scripts/image_signing/common_minimal.sh
+++ b/scripts/image_signing/common_minimal.sh
@@ -518,4 +518,3 @@
   ${FUTILITY} dump_fmap "$1" | grep -q KEY_RO
 }
 
-trap "cleanup_temps_and_mounts" EXIT