bpf/tests: Fix copy-and-paste error in double word test

[ Upstream commit ae7f47041d928b1a2f28717d095b4153c63cbf6a ]

This test now operates on DW as stated instead of W, which was
already covered by another test.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210721104058.3755254-1-johan.almbladh@anyfinetworks.com


Signed-off-by: Sasha Levin <sashal@kernel.org>