linux-yocto/4.x: configuration updates

linux-yocto/4.x: configuration updates

Integrating a series to expliclity set the quark build to 32 bits
and avoid 64 bit x86 defaults.

We also have a series of commits that fix configuration warnings on
x86 platforms:

 intel-quark.cfg: Explicitly disable CONFIG_64BIT
 common-pc-drivers.cfg: Remove I2O configs
 features: Fix dependencies and =m vs =y discrepancies for corei7
 intel-core2-32.cfg: Explicitly disable CONFIG_64BIT
 features: Add 6lowpan feature and add it where necessary

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>