distro/poky: Add Debian 7.5 and 7.6 version as validated

(From meta-yocto rev: b3191f636e19bda563e7b4d0ec6575159760830e)

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-yocto/conf/distro/poky.conf

@@ -88,6 +88,8 @@ SANITY_TESTED_DISTROS ?= " \
             Debian-7.2 \n \
             Debian-7.3 \n \
             Debian-7.4 \n \
+            Debian-7.5 \n \
+            Debian-7.6 \n \
             SUSE-LINUX-12.2 \n \
             openSUSE-project-12.3 \n \
             openSUSE-project-13.1 \n \