merge SLES and SLED branding package to yast2-branding-SLE

I see problem with obsolete/provide removed packages, but spec-files yast2-branding-SLES.spec and yast2_branding-SLED.spec had a 'Provides: yast2-branding' set which is also set now in yast2-branding-SLE.spec.
Therefore my thinking was that no change concerning provide/obsolete is needed here.