args: fix documentation to reflect the correct numbers

The macro uses up to 15 arguments.  Reflect this in the top level comment.

Link: https://lkml.kernel.org/r/20251201201018.765475-1-andriy.shevchenko@linux.intel.com
Fixes: d51e783 ("lsm: count the LSMs enabled at compile time")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: andy-shev

include/linux/args.h

@@ -6,9 +6,9 @@
 /*
  * How do these macros work?
  *
- * In __COUNT_ARGS() _0 to _12 are just placeholders from the start
+ * In __COUNT_ARGS() _0 to _15 are just placeholders from the start
  * in order to make sure _n is positioned over the correct number
- * from 12 to 0 (depending on X, which is a variadic argument list).
+ * from 15 to 0 (depending on X, which is a variadic argument list).
  * They serve no purpose other than occupying a position. Since each
  * macro parameter must have a distinct identifier, those identifiers
  * are as good as any.