recipetool: create: fix incorrect URL variable usage

recipetool: create: fix incorrect URL variable usage

We have two variables here, srcuri and fetchuri. srcuri is what
eventually ends up in the recipe, whereas fetchuri is what we actually
pass to the fetcher when we fetch the source within recipetool -
sometimes these need to be different particularly for an upcoming patch
to handle automatically setting the branch parameter. In OE-Core
revision 9a47a6690052ef943c0d4760630ee630fb012153 I erroneously changed
the call to scriptutils.fetch_url() to pass srcuri instead of fetchuri -
this likely didn't have any ill effect, but change it back to passing
fetchuri to match the original intent.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>