wic: use image recipe sysroot as default

Switched from using wic-tools recipe sysroot to using
image sysroot in wic script. This way is more logical
and consistent with the way wic uses other artifacts.

[YOCTO #11017]

(From OE-Core rev: fc94feda4f4785bc020413943c80050adea13dc0)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/wic

@@ -190,7 +190,7 @@ def wic_create_subcommand(args, usage_str):
         rootfs_dir = get_bitbake_var("IMAGE_ROOTFS", options.image_name)
         kernel_dir = get_bitbake_var("DEPLOY_DIR_IMAGE", options.image_name)
         native_sysroot = get_bitbake_var("RECIPE_SYSROOT_NATIVE",
-                                         "wic-tools", cache=False)
+                                         options.image_name) #, cache=False)
     else:
         if options.build_rootfs:
             raise WicError("Image name is not specified, exiting. "