T7026: Use vpp patches during build as they not applied

Patches for VPP are not applied due to specific to the vpp repo
structure, so we cannot use standard included to build.py
function 'apply_patches' to patch the vpp sources.
Use explicit patch in the "build_cmd" as a workaround and the
simplest fix.

scripts/package-build/vpp/package.toml

@@ -15,6 +15,12 @@ rsync -av ../vyos-vpp-patches/patches/vpp/ ../patches/vpp/
 """
 
 build_cmd = """
+# Patches for vpp should applied here
+for patch in ../patches/vpp/*.patch; do
+    echo "I: build_cmd Applying patch $patch..."
+    git apply "$patch" || { echo "Failed to apply patch $patch"; exit 1; }
+done
+
 make UNATTENDED=yes install-dep
 make pkg-deb
 cp build-root/*.deb ../