uninative-tarball: fix dependency on patchelf

DEPENDS doesn't actually add the dependency on patchelf-native to the
populate_sdk task. SDK_DEPENDS does this, but move the append to after
inheriting the base class so it does not get overwritten.

Without this, uninative-tarball fails to build in a clean workspace on a
system without patchelf.

[YOCTO #7467]

Signed-off-by: Tyler Hall <tylerwhall@gmail.com>
Acked-by: Randy Witt <randy.e.witt@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>