Fix smart charger values

Fix all smart charger values by having boards provide the RSENSE values
and perform the register calculations in the code.

The galp3-c, galp5, gaze16, and gaze17 do not seem to have the same
behavior as the rest of the boards, and further investigation is needed.
In the mean time, reduce their charge current values to preserve current
behavior.

Ref: OZ26786-DS v1.0
Ref: bq24780S Rev. C datasheet
Signed-off-by: Tim Crawford <tcrawford@system76.com

doc/adding-a-new-board.md

@@ -2,7 +2,9 @@
 
 ## Charger parameters
 
-- `CHARGER_CHARGE_CURRENT`: Currently the same for all boards (1536).
+- `CHARGER_ADAPTER_RSENSE`: The adapter RSENSE value in milliohms.
+- `CHARGER_BATTERY_RSENSE`: The battery RSENSE value in milliohms.
+- `CHARGER_CHARGE_CURRENT`: The desired charge current in milliamps.
 - `CHARGER_CHARGE_VOLTAGE`: On the battery, look for 充电限制电压 (charge limit
   voltage). Convert this from volts to millivolts.
 - `CHARGER_INPUT_CURRENT`: On the charger, look for DC output. Convert the
@@ -10,23 +12,28 @@
 
 #### Example
 
-The gaze15 battery has
+The gaze15 battery has:
 
 ```
 充电限制电压: 16.8Vdc
 ```
 
-and its charger has
+Its charger has:
 
 ```
 DC OUTPUT (输出/輸出): 19.5V⎓9.23A 180W
 ```
 
-This gives
+The schematics show it uses a 0.005 ohm sense resistor for both the adapter and
+the battery.
+
+This gives:
 
 ```
 CFLAGS+=\
-	-DCHARGER_CHARGE_CURRENT=1536 \
+	-DCHARGER_ADAPTER_RSENSE=5 \
+	-DCHARGER_BATTERY_RSENSE=5 \
+	-DCHARGER_CHARGE_CURRENT=3072 \
 	-DCHARGER_CHARGE_VOLTAGE=16800 \
 	-DCHARGER_INPUT_CURRENT=9230
 ```