Add abbility to specify dpdk tarball download base url

Change-Id: Ieceb0b1f4ab69609961d8946f627dd9311963da5
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/dpdk/Makefile b/dpdk/Makefile
index dabbf6a..e6e2b5f 100644
--- a/dpdk/Makefile
+++ b/dpdk/Makefile
@@ -24,8 +24,9 @@
 B := $(DPDK_BUILD_DIR)
 I := $(DPDK_INSTALL_DIR)
 DPDK_VERSION ?= 2.2.0
+DPDK_BASE_URL ?= http://dpdk.org/browse/dpdk/snapshot
 DPDK_TARBALL := dpdk-$(DPDK_VERSION).tar.gz
-DPDK_TAR_URL := http://dpdk.org/browse/dpdk/snapshot/$(DPDK_TARBALL)
+DPDK_TAR_URL := $(DPDK_BASE_URL)/$(DPDK_TARBALL)
 DPDK_2.1.0_TARBALL_MD5_CKSUM := 205a0d12bfd6eb717d57506272f43519
 DPDK_2.2.0_TARBALL_MD5_CKSUM := 22e2fd68cd5504f43fe9a5a6fd6dd938
 DPDK_SOURCE := $(B)/dpdk-$(DPDK_VERSION)