Fixes the following W=1 kernel build warning(s):
drivers/net/xen-netfront.c: In function ‘store_rxbuf’:
drivers/net/xen-netfront.c:2416:16: warning: variable ‘target’ set but not used [-Wunused-but-set-variable]
drivers/net/xen-netfront.c:1592: warning: Function parameter or member 'dev' not described in 'netfront_probe'
drivers/net/xen-netfront.c:1592: warning: Function parameter or member 'id' not described in 'netfront_probe'
drivers/net/xen-netfront.c:1669: warning: Function parameter or member 'dev' not described in 'netfront_resume'
drivers/net/xen-netfront.c:2313: warning: Function parameter or member 'dev' not described in 'netback_changed'
drivers/net/xen-netfront.c:2313: warning: Function parameter or member 'backend_state' not described in 'netback_changed'
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: Yonghong Song <yhs@xxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: KP Singh <kpsingh@xxxxxxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Cc: bpf@xxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>