distrodata_class: checkpkg make usage of latest_versionstring methods in bitbake...

distrodata_class: checkpkg make usage of latest_versionstring methods in bitbake fetcher

Because methods for get latest version of upstream package are now available
into bitbake removes duplicated code and make use of it.

Compatibility testing was made running distrodata class and the result files
can be found at:

https://bugzilla.yoctoproject.org/show_bug.cgi?id=1813

[YOCTO #1813]

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>