recipe_sanity.bbclass: skip DataSmart in recipe_sanity_eh()

recipe_sanity.bbclass: skip DataSmart in recipe_sanity_eh()

Fixed:
$ bitbake quilt -crecipe_sanity
  File "/path/to/poky/bitbake/lib/bb/siggen.py", line 261, in dump_sigtask
    p = pickle.dump(data, stream, -1)
PicklingError: Can't pickle <COWDict Level: 1 Current Keys: 0>:
attribute lookup bb.COW.C failed

This is because of:
cfgdata[k] = d.getVar(k, 0)

If d.getVar(k, 0) is a DataSmart (for example, BB_ORIGENV), it won't
have the attribute of bb.COW.C, so the error happend.

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>