Fix order of parameters to BTA_GATTC_Open

Different order of parameters in different flavours of method caused
bug in btif_gatt_client.cc, where every client would be started as
opportunistic. This issue was introduced in commit
fb052951

Bug: 34951749
Test: sl4a GattReadTest was flaky without this patch
Change-Id: I243b11bd8e2c0da9f01cbd3eab95dc808bd54006