UPSTREAM: binder: avoid kernel vm_area for buffer fixups

Refactor the functions to validate and fixup struct
binder_buffer pointer objects to avoid using vm_area
pointers. Instead copy to/from kernel space using
binder_alloc_copy_to_buffer() and
binder_alloc_copy_from_buffer(). The following
functions were refactored:

	refactor binder_validate_ptr()
	binder_validate_fixup()
	binder_fixup_parent()

(cherry pick from commit db6b0b810bf945d1991917ffce0e93383101f2fa)
Bug: 67668716
Signed-off-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Change-Id: Ic222af9b6c56bf48fd0b65debe981d19a7809e77