devtool: modify: fix usage on the kernel

devtool: modify: fix usage on the kernel

When using devtool modify on the kernel, we have to do a bit of a dance
with tinfoil instances because we only find out that we're working on a
kernel recipe after tinfoil is initialised, but then we need to build
kern-tools-native which we're doing just by running bitbake directly.
With the tinfoil2 changes, a datastore for the recipe that we were
keeping around across the opening and closing of tinfoil is no longer
able to be used. Re-parse the recipe to avoid this problem.

(In future this whole thing will be able to be done in the same tinfoil
instance thanks to tinfoil2, but that refactoring is yet to be done.)

(From OE-Core rev: 06127d0115ba449bf04e2579cd1010065e0ed6e3)

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