core: OSRAM Lightify A19 Tunable White bulb incorrectly shows RGB controls

#21060 The problem

1. OSRAM Lightify A19 Tunable White bulb incorrectly shows RGB controls.
2. MAX Mireds shows 500 but should only be 370.

Environment

• Home Assistant Core release with the issue: 0.115.0b1 back to 0.110.
• Last working Home Assistant Core release (if known): None
• Operating environment (OS/Container/Supervised/Core):

arch | x86_64
chassis | desktop
dev | false
docker | true
docker_version | 19.03.12
hassio | true
host_os | Debian GNU/Linux 10 (buster)
installation_type | Home Assistant Supervised
os_name | Linux
os_version | 4.19.0-10-amd64
python_version | 3.8.4
supervisor | 242
timezone | America/Vancouver
version | 0.115.0b1
virtualenv | false

• Integration causing this issue: ZHA
• Link to integration documentation on our website:

Problem-relevant configuration.yaml

{
  "node_descriptor": "NodeDescriptor(byte1=1, byte2=64, mac_capability_flags=142, manufacturer_code=48042, maximum_buffer_size=64, maximum_incoming_transfer_size=0, server_mask=0, maximum_outgoing_transfer_size=0, descriptor_capability_field=3)",
  "endpoints": {
    "3": {
      "profile_id": 260,
      "device_type": "0x0102",
      "in_clusters": [
        "0x0000",
        "0x0003",
        "0x0004",
        "0x0005",
        "0x0006",
        "0x0008",
        "0x0300",
        "0x0b04",
        "0xfc0f"
      ],
      "out_clusters": [
        "0x0019"
      ]
    }
  },
  "manufacturer": "OSRAM",
  "model": "LIGHTIFY A19 Tunable White",
  "class": "zhaquirks.osram.a19twhite.A19TunableWhite"
}

Traceback/Error logs

Additional information