net: mscc: ocelot: Fix some struct initializations

Clang warns:

drivers/net/ethernet/mscc/ocelot_ace.c:335:37: warning: suggest braces
around initialization of subobject [-Wmissing-braces]
        struct ocelot_vcap_u64 payload = { 0 };
                                           ^
                                           {}
drivers/net/ethernet/mscc/ocelot_ace.c:336:28: warning: suggest braces
around initialization of subobject [-Wmissing-braces]
        struct vcap_data data = { 0 };
                                  ^
                                  {}
drivers/net/ethernet/mscc/ocelot_ace.c:683:37: warning: suggest braces
around initialization of subobject [-Wmissing-braces]
        struct ocelot_ace_rule del_ace = { 0 };
                                           ^
                                           {}
drivers/net/ethernet/mscc/ocelot_ace.c:743:28: warning: suggest braces
around initialization of subobject [-Wmissing-braces]
        struct vcap_data data = { 0 };
                                  ^
                                  {}
4 warnings generated.

One way to fix these warnings is to add additional braces like Clang
suggests; however, there has been a bit of push back from some
maintainers[1][2], who just prefer memset as it is unambiguous, doesn't
depend on a particular compiler version[3], and properly initializes all
subobjects. Do that here so there are no more warnings.

[1]: https://lore.kernel.org/lkml/022e41c0-8465-dc7a-a45c-64187ecd9684@amd.com/
[2]: https://lore.kernel.org/lkml/20181128.215241.702406654469517539.davem@davemloft.net/
[3]: https://lore.kernel.org/lkml/20181116150432.2408a075@redhat.com/

Fixes: b5962294 ("net: mscc: ocelot: Add support for tcam")
Link: https://github.com/ClangBuiltLinux/linux/issues/505


Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>