Currently, the `ip ila` command tries to initialize a genl context
even when we just want to see the help for the command, which doesn't
require to talk to the kernel at all.
Delay genl initialization, which can fail if the module isn't loaded,
until the point where we will actually need it.
Fixes: ec71cae0bb ("ila: Support for configuring ila to use netfilter hook")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
All users of genl have the same code to open a genl socket and resolve
the family for their specific protocol. Introduce a helper to initialize
the handle, and use it in all the genl code.
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>