power: supply: axp288_fuel_gauge: Drop retry logic from fuel_gauge_reg_readb()

The I2C-bus to the XPower AXP288 is shared between the Linux kernel and
the SoCs P-Unit. The P-Unit has a semaphore which the kernel must "lock"
before it may use the bus. This semaphore is automatically taken by the
I2C-bus-driver.

The retry on -EBUSY logic in fuel_gauge_reg_readb() likely was added to
deal with the I2C-bus-drive returning -EBUSY when it failed to take the
semaphore, but this really should never happen. The semaphore code even
has a WARN_ON(ret) to log a kernel backtrace if this does somehow happen,
when this happens something is seriously wrong and the system typically
freezes soon afterwards.

TL;DR: the regmap_read() should never fail with -EBUSY so the retries
are unnecessary.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/axp288_fuel_gauge.c

@@ -76,7 +76,6 @@
 #define FG_LOW_CAP_CRIT_THR			4   /* 4 perc */
 #define FG_LOW_CAP_SHDN_THR			0   /* 0 perc */
 
-#define NR_RETRY_CNT				3
 #define DEV_NAME				"axp288_fuel_gauge"
 
 /* 1.1mV per LSB expressed in uV */
@@ -132,15 +131,10 @@ static enum power_supply_property fuel_gauge_props[] = {
 
 static int fuel_gauge_reg_readb(struct axp288_fg_info *info, int reg)
 {
-	int ret, i;
 	unsigned int val;
+	int ret;
 
-	for (i = 0; i < NR_RETRY_CNT; i++) {
-		ret = regmap_read(info->regmap, reg, &val);
-		if (ret != -EBUSY)
-			break;
-	}
-
+	ret = regmap_read(info->regmap, reg, &val);
 	if (ret < 0) {
 		dev_err(&info->pdev->dev, "Error reading reg 0x%02x err: %d\n", reg, ret);
 		return ret;