deb-pkg: remove obsolete -isp option to dpkg-gencontrol

The -isp option has been deprecated, after it became the default
behaviour back in 2006.

Since dpkg 1.17.11, dpkg-gencontrol emits a warning on -isp usage.

References: https://bugs.debian.org/215233
Signed-off-by: Asbjoern Sloth Toennesen <asbjorn@asbjorn.biz>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/package/builddeb

@@ -64,7 +64,7 @@ create_package() {
 	fi
 
 	# Create the package
-	dpkg-gencontrol -isp $forcearch -Vkernel:debarch="${debarch:-$(dpkg --print-architecture)}" -p$pname -P"$pdir"
+	dpkg-gencontrol $forcearch -Vkernel:debarch="${debarch:-$(dpkg --print-architecture)}" -p$pname -P"$pdir"
 	dpkg --build "$pdir" ..
 }