x86: bpf_jit_comp: can call module_free() from any context

It looks like we can call module_free()/vfree() from softirq context,
so no longer need a wrapper and a work_struct.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>