roms/SLOF: Update submodule to latest status

We need the latest fixes for building the libc and libnet
of SLOF for the s390-ccw network bootloader firmware.
Signed-off-by: NThomas Huth <thuth@redhat.com>
Message-Id: <1499863793-18627-9-git-send-email-thuth@redhat.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

SLOF @ 834113a1

-Subproject commit 66d250ef0fd06bb88b7399b9563b5008201f2d63
+Subproject commit 834113a1c67d6fb53dea153c3313d182238f2d36