lib/win_minmax: use /* notation for regular comments

lib/win_minmax: use /* notation for regular comments

Don't use kernel-doc "/**" notation for non-kernel-doc comments.
Prevents a kernel-doc warning:

lib/win_minmax.c:31: warning: expecting prototype for lib/minmax.c(). Prototype was for minmax_subwin_update() instead

Link: https://lkml.kernel.org/r/20230102211614.26343-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>