scripts/dtc: dt_to_config - kernel config options for a devicetree

Determining which kernel config options need to be enabled for a
given devicetree can be a painful process.  Create a new tool to
find the drivers that may match a devicetree node compatible,
find the kernel config options that enable the driver, and
optionally report whether the kernel config option is enabled.

Signed-off-by: Gaurav Minocha <gaurav.minocha.os@gmail.com>
Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>