selftests: drv-net: tso: fix the GRE device name

The device type for IPv4 GRE is "gre" not "ipgre",
unlike for IPv6 which uses "ip6gre".

Not sure how I missed this when writing the test, perhaps
because all HW I have access to is on an IPv6-only network.

Fixes: 0d0f417 ("selftests: drv-net: add a simple TSO test")
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250604012031.891242-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

tools/testing/selftests/drivers/net/hw/tso.py

@@ -216,7 +216,7 @@ def main() -> None:
             ("",            "6", "tx-tcp6-segmentation",          None),
             ("vxlan",        "", "tx-udp_tnl-segmentation",       ("vxlan",  True,  "id 100 dstport 4789 noudpcsum")),
             ("vxlan_csum",   "", "tx-udp_tnl-csum-segmentation",  ("vxlan",  False, "id 100 dstport 4789 udpcsum")),
-            ("gre",         "4", "tx-gre-segmentation",           ("ipgre",  False,  "")),
+            ("gre",         "4", "tx-gre-segmentation",           ("gre",    False,  "")),
             ("gre",         "6", "tx-gre-segmentation",           ("ip6gre", False,  "")),
         )