net: ipv4: ipmr: ipmr_queue_xmit(): Drop local variable `dev'

The variable is used for caching of rt->dst.dev. The netdevice referenced
therein does not change during the scope of validity of that local. At the
same time, the local is only used twice, and each of these uses will end up
in a different function in the following patches, further eliminating any
use the local could have had.

Drop the local altogether and inline the uses.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/c80600a4b51679fe78f429ccb6d60892c2f9e4de.1750113335.git.petrm@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>