netfilter: ip6t_srh: fix UAPI kernel-doc comments format

Fix the kernel-doc format for struct members to be "@member" instead of
"@ member" to avoid kernel-doc warnings.

Warning: ip6t_srh.h:60 struct member 'next_hdr' not described in 'ip6t_srh'
Warning: ip6t_srh.h:60 struct member 'hdr_len' not described in 'ip6t_srh'
Warning: ip6t_srh.h:60 struct member 'segs_left' not described
 in 'ip6t_srh'
Warning: ip6t_srh.h:60 struct member 'last_entry' not described
 in 'ip6t_srh'
Warning: ip6t_srh.h:60 struct member 'tag' not described in 'ip6t_srh'
Warning: ip6t_srh.h:60 struct member 'mt_flags' not described in 'ip6t_srh'
Warning: ip6t_srh.h:60 struct member 'mt_invflags' not described
 in 'ip6t_srh'
Warning: ip6t_srh.h:93 struct member 'next_hdr' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'hdr_len' not described in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'segs_left' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'last_entry' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'tag' not described in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'psid_addr' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'nsid_addr' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'lsid_addr' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'psid_msk' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'nsid_msk' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'lsid_msk' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'mt_flags' not described
 in 'ip6t_srh1'
Warning: ip6t_srh.h:93 struct member 'mt_invflags' not described
 in 'ip6t_srh1'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>