mfd: max77620: Use single-byte writes on MAX77620

The MAX77620 doesn't support bulk writes, so make sure the regmap code
breaks bulk writes into multiple single-byte writes.

Note that this is mostly cosmetic because currently only the RTC sub-
driver uses bulk writes and the RTC driver ends up using a different
regmap on the MAX77620 anyway. However, it seems like a good idea to
make this change now in order to avoid running into issues if bulk
writes are ever used by other sub-drivers sometime down the road.

Signed-off-by: Thierry Reding <[e-mail]>
Acked-by: Jon Hunter <[e-mail]>
Tested-by: Jon Hunter <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/max77620.c

···
 	.rd_table = &max77620_readable_table,
 	.wr_table = &max77620_writable_table,
 	.volatile_table = &max77620_volatile_table,
+	.use_single_write = true,
 };
 
 static const struct regmap_config max20024_regmap_config = {