Rename hciops_set_class to write_class

Since hciops_set_class isn't (anymore) part of the exported adapter_ops
callbacks it's better to change it's name to avoid confusion.
diff --git a/plugins/hciops.c b/plugins/hciops.c
index 3b6e11f..4af137c 100644
--- a/plugins/hciops.c
+++ b/plugins/hciops.c
@@ -1267,7 +1267,7 @@
 	adapter_mode_changed(adapter, rp->enable);
 }
 
-static int hciops_set_class(int index, uint32_t class)
+static int write_class(int index, uint32_t class)
 {
 	write_class_of_dev_cp cp;
 
@@ -1317,7 +1317,7 @@
 						(num * 3 + 1), &cp) < 0)
 		return -errno;
 
-	return hciops_set_class(index, WANTED_COD(index));
+	return write_class(index, WANTED_COD(index));
 }
 
 static void write_class_complete(int index, uint8_t status)
@@ -1349,7 +1349,7 @@
 					(CURRENT_COD(index) & LIMITED_BIT))
 		hciops_set_limited_discoverable(index, FALSE);
 	else
-		hciops_set_class(index, WANTED_COD(index));
+		write_class(index, WANTED_COD(index));
 }
 
 static inline void cmd_complete(int index, void *ptr)
@@ -2409,7 +2409,7 @@
 
 	DBG("Changing Major/Minor class to 0x%06x", WANTED_COD(index));
 
-	err = hciops_set_class(index, WANTED_COD(index));
+	err = write_class(index, WANTED_COD(index));
 	if (err < 0)
 		error("Adapter class update failed: %s (%d)",
 						strerror(-err), -err);
@@ -2986,7 +2986,7 @@
 
 	DBG("Changing service classes to 0x%06x", WANTED_COD(index));
 
-	err = hciops_set_class(index, WANTED_COD(index));
+	err = write_class(index, WANTED_COD(index));
 	if (err < 0)
 		error("Adapter class update failed: %s (%d)",
 						strerror(-err), -err);
@@ -3079,7 +3079,7 @@
 		return 0;
 	}
 
-	return hciops_set_class(index, WANTED_COD(index));
+	return write_class(index, WANTED_COD(index));
 }
 
 static struct btd_adapter_ops hci_ops = {