Kbuild: Fix deb-pkg target to work with kernel versions ending with -<text-without-digit>

If CONIFIG_LOCALVERSION is set for example to -loop, the following error
message was generated.

dpkg-deb - error: Debian revision (`loop') doesn't contain any digits
dpkg-deb: 1 errors in control file

The patch solves this by adding a numeric revision to package version.
Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/package/builddeb

@@ -13,6 +13,7 @@ set -e
 
 # Some variables and settings used throughout the script
 version=$KERNELRELEASE
+revision=`cat .version`
 tmpdir="$objtree/debian/tmp"
 packagename=linux-$version
 
@@ -65,7 +66,7 @@ done
 name="Kernel Compiler <$(id -nu)@$(hostname -f)>"
 # Generate a simple changelog template
 cat <<EOF > debian/changelog
-linux ($version) unstable; urgency=low
+linux ($version-$revision) unstable; urgency=low
 
   * A standard release