poky.conf: bump version for 5.2.1

(From meta-yocto rev: 73ef61468496fd129b90c3f0afe26859b441b26b)

Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta-poky/conf/distro/poky.conf

@@ -1,6 +1,6 @@
 DISTRO = "poky"
 DISTRO_NAME = "Poky (Yocto Project Reference Distro)"
-DISTRO_VERSION = "5.2"
+DISTRO_VERSION = "5.2.1"
 DISTRO_CODENAME = "walnascar"
 SDK_VENDOR = "-pokysdk"
 SDK_VERSION = "${@d.getVar('DISTRO_VERSION').replace('snapshot-${METADATA_REVISION}', 'snapshot')}"