bitbake: toaster: modify SQL data type constraints

bitbake: toaster: modify SQL data type constraints

This patch modifies the data type constraints for the SQL
fields.

The original constraints have been based on guess worked, and
they weren't strictly enforced for sqlite. On MySQL, the
constraints are strictly enforced, and need to match the real
data that we have.

After measuring data on sample builds, the new constraints
have been validated to work with MySQL, and this patch updates
the database schema with the new field types / constraints.

(Bitbake rev: aaefbc0b4e7484d6f4854ce49602821a6e4adc4b)

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>