bitbake: fetch2: raise an exception if user specifies protocol=git with http://

bitbake: fetch2: raise an exception if user specifies protocol=git with 

It is a common mistake to use http:// and protocol=git when attempting
to fetch from a git repository using the http protocol; if this is
detected then throw an error explaining that you need to use git:// with
protocol=http instead.

(Bitbake rev: 5bc4930c1638db16bcd5f9c8cfc4081f9ffc192b)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>