misc: ad525x_dpot: Use str_enabled_disabled() in sysfs_show_reg()

Remove hard-coded strings by using the str_enabled_disabled() helper
function and silence the following Coccinelle/coccicheck warning
reported by string_choices.cocci:

  opportunity for str_enabled_disabled(..)

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://lore.kernel.org/r/20250820102734.760844-2-thorsten.blum@linux.dev


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>