pypi.bbclass: Set CVE_PRODUCT to PYPI_PACKAGE

pypi.bbclass: Set CVE_PRODUCT to PYPI_PACKAGE

The CVE product name for PyPI packages is (usually) the same as the PyPI
package name (and not our recipe name), so use that as the default.

Signed-off-by: Alex Kiernan <alexk@zuma.ai>
Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 61f6b0ad09bf87cdc2d3f08770b7c44cad1d0e58)
Signed-off-by: Sanjay Chitroda <schitrod@cisco.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>