ipv6: Re-arrange code in rt6_probe()
ipv6: Re-arrange code in rt6_probe()

It is a prep work for the next patch to remove write_lock
from rt6_probe().

1. Reduce the number of if(neigh) check.  From 4 to 1.
2. Bring the write_(un)lock() closer to the operations that the
   lock is protecting.

Hopefully, the above make rt6_probe() more readable.

Signed-off-by: Martin KaFai Lau <2c0d8efbe28c4f7a45c3ab30c984ed2c126716bd@fb.com>
Cc: Hannes Frederic Sowa <331be22c6b63ca3e0a03d408c2d906b1b02cd5f2@stressinduktion.org>
Cc: Julian Anastasov <84572ef2253ef81e2d8cd8c65849f4d9a3881f47@ssi.bg>
Cc: YOSHIFUJI Hideaki <843235c427d233c8a3c962f92f91acf3da14a1ed@miraclelinux.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs