fs/orangefs: Allow 2 more characters in do_c_string()

The do_k_string() and do_c_string() functions do essentially the same
thing which is they add a string and a comma onto the end of an existing
string.  At the end, the caller will overwrite the last comma with a
newline.  Later, in orangefs_kernel_debug_init(), we add a newline to
the string.

The change to do_k_string() is just cosmetic.  I moved the "- 1" to
the other side of the comparison and made it "+ 1".  This has no
effect on runtime, I just wanted the functions to match each other
and the rest of the file.

However in do_c_string(), I removed the "- 2" which allows us to print
two extra characters.  I noticed this issue while reviewing the code
and I doubt affects anything in real life.  My guess is that this was
double counting the comma and the newline.  The "+ 1" accounts for
the newline, and the caller will delete the final comma which ensures
there is enough space for the newline.

Removing the "- 2" lets us print 2 more characters, but mainly it makes
the code more consistent and understandable for reviewers.

Fixes: 44f46410 ("orangefs: clean up debugfs globals")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>