Add python3 to the build scripts

Several packages have been upgraded to use python3 in the
latest yocto version, therefore the build scripts needs to
incorporate that dependency.

Change-Id: I300295f0434f690c795ce863f159ab9980af1a48
Signed-off-by: Saqib Khan <khansa@us.ibm.com>
diff --git a/openpower-build-setup.sh b/openpower-build-setup.sh
index 6062389..fa79635 100755
--- a/openpower-build-setup.sh
+++ b/openpower-build-setup.sh
@@ -73,6 +73,7 @@
 	"perl(YAML)" \
 	"perl(XML::LibXML)" \
 	python \
+	python3 \
 	tar \
 	unzip \
 	vim \
@@ -114,6 +115,7 @@
 	libxml2-utils \
 	language-pack-en \
 	python \
+	python3 \
 	texinfo \
 	unzip \
 	vim-common \