bpf: net: Change do_ip_getsockopt() to take the sockptr_t argument

bpf: net: Change do_ip_getsockopt() to take the sockptr_t argument

Similar to the earlier patch that changes sk_getsockopt() to
take the sockptr_t argument.  This patch also changes
do_ip_getsockopt() to take the sockptr_t argument such that
a latter patch can make bpf_getsockopt(SOL_IP) to reuse
do_ip_getsockopt().

Note on the change in ip_mc_gsfget().  This function is to
return an array of sockaddr_storage in optval.  This function
is shared between ip_get_mcast_msfilter() and
compat_ip_get_mcast_msfilter().  However, the sockaddr_storage
is stored at different offset of the optval because of
the difference between group_filter and compat_group_filter.
Thus, a new 'ss_offset' argument is added to ip_mc_gsfget().

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002828.2890585-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>