Require libosmocore 1.1.0

Older commit made use of gsm48_decode_bcd_number2(), which is available
in libosmocore 1.1.0 onwards, but forgot to increase configure.ac
requirements.

Fixes: fb625041601c525c23c96482250157dddb0941a4
Change-Id: I89b37be55fc4ba22b90e9aab9a5989573df2ae38
diff --git a/debian/control b/debian/control
index 272fd79..3392f83 100644
--- a/debian/control
+++ b/debian/control
@@ -7,7 +7,7 @@
                pkg-config,
                libdpkg-perl, git,
                dh-autoreconf,
-               libosmocore-dev (>= 0.8.0),
+               libosmocore-dev (>= 1.1.0),
                osmo-gsm-manuals-dev
 Standards-Version: 3.9.6
 Vcs-Browser: http://git.osmocom.org/osmo-ggsn/