bitbake: data_smart: Ensure all possible overrides are cached including those with...

bitbake: data_smart: Ensure all possible overrides are cached including those with '_' in the name

Unfortunately we've been neglecting to pay the correct tributes to the
cookie monster and hence the datastore is malfunctioning.

Currently tributes are only paid on the last part of a variable after
the last "_" character. We need to split by *all* "_" characters since
an override may contain the character.

This fixes the code so the correct number of tributes are made. Paradoxically
parsing appears to be faster after this change.

(Bitbake rev: d1c712fd3a59fa804e6fd451612c30487671f3a2)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>