fdo#71217 PDF Import: Fix importing of JPEG images

Change-Id: Ic0902a3f9340d2d05be05d13d98f168879b4c3e3
Reviewed-on: https://gerrit.libreoffice.org/9120
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>