iio: adc: ingenic-adc: rename ingenic_adc_enable_unlocked() function

iio: adc: ingenic-adc: rename ingenic_adc_enable_unlocked() function

Rename ingenic_adc_enable_unlocked() to __ingenic_adc_enable() to
better reflect that this helper must be called with the lock held.

Signed-off-by: Felipe Ribeiro de Souza <felipers@ime.usp.br>
Co-developed-by: Lucas Ivars Cadima Ciziks <lucas@ciziks.com>
Signed-off-by: Lucas Ivars Cadima Ciziks <lucas@ciziks.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>