netlink: fix spelling mistake in dump size assert

Commit 2c7bc10d ("netlink: add macro for checking dump ctx size")
misspelled the name of the assert as asset, missing an R.

Reported-by: Ido Schimmel <idosch@idosch.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/20230123222224.732338-1-kuba@kernel.org


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