fix instruction: adc (3rd arg is mux, not pad)

this might be wrong in ulp.h as the wrong implementation
was inspired from that.

the tech ref and the prog guide both talk about the mux (not the pad).

Author: ThomasWaldmann

esp32_ulp/opcodes.py

@@ -378,9 +378,9 @@ def i_wait(cycles):
     return _delay.all
 
 
-def i_adc(reg_dest, adc_idx, pad_idx):
+def i_adc(reg_dest, adc_idx, mux):
     _adc.dreg = get_reg(reg_dest)
-    _adc.mux = get_imm(pad_idx) + 1
+    _adc.mux = get_imm(mux)
     _adc.sar_sel = get_imm(adc_idx)
     _adc.unused1 = 0
     _adc.cycles = 0

tests/compat/io.S

@@ -6,4 +6,4 @@
             i2c_rd 0x10, 7, 0, 0
             i2c_wr 0x23, 0x42, 7, 0, 1
 
-            adc r0, 0, 1
+            adc r0, 1, 2