[nrf fromlist] samples: bluetooth: reduce RAM for hci_ipc df ll_sw_split

After stack size increase for IPC RAM now needs to be
reduced in other areas.

Presumably these buffers can all be decreased by 1.

Upstream PR: zephyrproject-rtos/zephyr#79729

Signed-off-by: Sean Madigan <[email protected]>

Author: sean-madigan

samples/bluetooth/hci_ipc/nrf5340_cpunet_df-bt_ll_sw_split.conf

@@ -16,7 +16,7 @@ CONFIG_BT_MAX_CONN=2
 # Host number of completed commands does not follow normal flow control.
 CONFIG_BT_BUF_CMD_TX_COUNT=10
 
-CONFIG_BT_BUF_EVT_RX_COUNT=16
+CONFIG_BT_BUF_EVT_RX_COUNT=15
 
 CONFIG_BT_BUF_EVT_RX_SIZE=255
 CONFIG_BT_BUF_ACL_RX_SIZE=255