Remove reference to ENOTDIR in the documented errors

for statfs(2). This is false, if the pathname specified
is a regular file, then the information for the file
system that the file lives on will be returned.

Approved by:	bmilekic (mentor)

lib/libc/sys/statfs.2

@@ -175,10 +175,6 @@ The
 system call
 fails if one or more of the following are true:
 .Bl -tag -width Er
-.It Bq Er ENOTDIR
-A component of the path prefix of
-.Fa path
-is not a directory.
 .It Bq Er ENAMETOOLONG
 The length of a component of
 .Fa path