IS_ENABLED should only be used for CONFIG_* symbols.
I have done a small test:
  #define REGMAP_ALLOW_WRITE_DEBUGFS
  IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS) returns 0.
  #define REGMAP_ALLOW_WRITE_DEBUGFS 0
  IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS) returns 0.
  #define REGMAP_ALLOW_WRITE_DEBUGFS 1
  IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS) returns 1.
  #define REGMAP_ALLOW_WRITE_DEBUGFS 2
  IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS) returns 0.
So fix the misuse of IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS) and switch to
use #if defined(REGMAP_ALLOW_WRITE_DEBUGFS) instead.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
        if (map->max_register || regmap_readable(map, 0)) {
                umode_t registers_mode;
 
-               if (IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS))
-                       registers_mode = 0600;
-               else
-                       registers_mode = 0400;
+#if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
+               registers_mode = 0600;
+#else
+               registers_mode = 0400;
+#endif
 
                debugfs_create_file("registers", registers_mode, map->debugfs,
                                    map, ®map_map_fops);