RootCanal: Disable LL tests based on controller features

Read the LE supported features mask to disable tests that
rely on LL privacy (LL/DDI/SCN/BV-13-C, LL/DDI/SCN/BV-14-C,
LL/DDI/SCN/BV-18-C)

Test: atest rootcanal_ll_test
Change-Id: Ice99137a4d4e7372fdad58df139b6ea5d330b9b6