uek-rpm: add update-el-x86; fix-up ol6/update-el

uek-rpm: add update-el-x86; fix-up ol6/update-el

The build env will start looking for uek-rpm/ol?/update-el-<arch>.
Add uek-rpm/ol6/update-el-x86, specifying 6.7.
Add uek-rpm/ol7/update-el-x86, specifying 7.3.

For now, leave uek-rpm/ol?/update-el.  Remove them later after we know
that there are no issues with using uek-rpm/ol?/update-el-x86.

Set uek-rpm/ol6/update-el to 6.7 which is the current UEK4 build env.
It was set previously to 6.6 but has been overridden by the build env.
The build env is about to be changed so that it will no longer override it.
uek-rpm/ol7/update-el has the correct value, 7.3, so no change is needed.

Delete the unused uek-rpm/ol6/update-el-ol6 and uek-rpm/ol7/update-el-ol7.

Orabug: 27004340
Signed-off-by: Chuck Anderson <chuck.anderson@oracle.com>