adc_ll_digi_set_pattern_table_len() function

Set pattern table length for digital controller. The pattern table that defines the conversion rules for each SAR ADC. Each table has 16 items, in which channel selection, resolution and attenuation are stored. When the conversion is started, the controller reads conversion rules from the pattern table one by one. For each controller the scan sequence has at most 16 different rules before repeating itself.