ACPI: fan: Optimize struct acpi_fan_fif

We don't need u64 to store the information about _FIF. There are two
booleans (fine_grain_ctrl and low_speed_notification) and one field
step_size which can take value from 1-9. There are no internal users
of revision field. So convert all fields to u8, by not directly
extracting the _FIF info the struct. Use an intermediate buffer to
extract and assign.

This will help to do u32 math using these fields. No functional
changes are expected.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: spandruvada

drivers/acpi/fan.h

@@ -30,10 +30,10 @@ struct acpi_fan_fps {
 };
 
 struct acpi_fan_fif {
-	u64 revision;
-	u64 fine_grain_ctrl;
-	u64 step_size;
-	u64 low_speed_notification;
+	u8 revision;
+	u8 fine_grain_ctrl;
+	u8 step_size;
+	u8 low_speed_notification;
 };
 
 struct acpi_fan {

drivers/acpi/fan_core.c

@@ -211,7 +211,8 @@ static int acpi_fan_get_fif(struct acpi_device *device)
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	struct acpi_fan *fan = acpi_driver_data(device);
 	struct acpi_buffer format = { sizeof("NNNN"), "NNNN" };
-	struct acpi_buffer fif = { sizeof(fan->fif), &fan->fif };
+	u64 fields[4];
+	struct acpi_buffer fif = { sizeof(fields), fields };
 	union acpi_object *obj;
 	acpi_status status;
 
@@ -232,6 +233,11 @@ static int acpi_fan_get_fif(struct acpi_device *device)
 		status = -EINVAL;
 	}
 
+	fan->fif.revision = fields[0];
+	fan->fif.fine_grain_ctrl = fields[1];
+	fan->fif.step_size = fields[2];
+	fan->fif.low_speed_notification = fields[3];
+
 err:
 	kfree(obj);
 	return status;