tests: Bluetooth: Tester: Set controller ACL buffer size

Change the ACL buffer sizes to be a higher value than the
default, as that caused some issues with the CIS established
event.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

Author: Thalley

tests/bluetooth/tester/overlay-bt_ll_sw_split.conf

@@ -67,3 +67,8 @@ CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=259
 # Set advertising/scan data length to support large BAP BASEs
 CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=191
 CONFIG_BT_CTLR_SCAN_DATA_LEN_MAX=191
+
+# ACL data sizes
+CONFIG_BT_BUF_ACL_TX_SIZE=251
+CONFIG_BT_BUF_ACL_RX_SIZE=255
+CONFIG_BT_CTLR_DATA_LENGTH_MAX=251