ANDROID: GKI: net: add vendor hooks for 'struct sock' lifecycle

Some vendors want to add a field when a 'sruct sock' is added so give a
hook to handle this.  Any memory allocated when
trace_android_rvh_sk_alloc() is called needs to be freed when
trace_android_rvh_sk_free() is called.

Note, if trace_android_rvh_sk_alloc() fails, be sure to be able to
handle this in trace_android_rvh_sk_free(), but that should not be an
issue as that needs to be addressed in vendor code that runs for 'struct
sock' objects that have been created before the vendor code is loaded no
matter what.

Bug: 171013716
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I9ed93e8bffef3cd8fbde4d62fc14596764a85304