[PATCH] iio: ina2xx-adc: fix regmap max_register off-by-one

[Harshit Mogalapalli]

regmap_config.max_register is supposed to store the highest valid
register but this driver assigns the number of registers
INA2XX_MAX_REGISTERS is 8, the highest valid register address is 7.

Fix this by subtracting 1 so max_register is inclusive.

Fixes: c43a102e67db ("iio: ina2xx: add support for TI INA2xx Power Monitors")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx>
---
Found by static analysis using smatch, code review and guess work.
NOT TESTED.  Please review carefully!
---
 drivers/iio/adc/ina2xx-adc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 857e1b69d6cd..d200b8e87839 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -116,7 +116,7 @@ static inline bool is_signed_reg(unsigned int reg)
 static const struct regmap_config ina2xx_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 16,
-	.max_register = INA2XX_MAX_REGISTERS,
+	.max_register = INA2XX_MAX_REGISTERS - 1,
 	.writeable_reg = ina2xx_is_writeable_reg,
 	.volatile_reg = ina2xx_is_volatile_reg,
 };
-- 
2.50.1