selftests: drv-net: add rss_api to the Makefile

I missed adding rss_api.py to the Makefile. The NIPA Makefile
checking script was scanning for shell scripts only, so it
didn't flag it either.

Fixes: 4d13c6c449af ("selftests: drv-net: test RSS Netlink notifications")
Reviewed-by: Simon Horman <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/drivers/net/hw/Makefile

···
 	irq.py \
 	loopback.sh \
 	pp_alloc_fail.py \
+	rss_api.py \
 	rss_ctx.py \
 	rss_input_xfrm.py \
 	tso.py \