regulator: fixed-helper: use the correct function name in comment

Use the correct function name and modify the function short description.
This prevents a kernel-doc warning:

drivers/regulator/fixed-helper.c:32: warning: expecting prototype for regulator_register_fixed_name(). Prototype was for regulator_register_always_on() instead

Signed-off-by: Randy Dunlap <[e-mail]>
Cc: Liam Girdwood <[e-mail]>
Cc: Mark Brown <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/regulator/fixed-helper.c

···
 }
 
 /**
- * regulator_register_fixed_name - register a no-op fixed regulator
+ * regulator_register_always_on - register an always-on regulator with a fixed name
  * @id: platform device id
  * @name: name to be used for the regulator
  * @supplies: consumers for this regulator