firmware: tisci: Drop all deprecated messages

firmware: tisci: Drop all deprecated messages

SYSFW v2020.01 and later versions no longer supports the below messages:
- TI_SCI_MSG_RM_RING_GET_CFG
- TISCI_MSG_RM_UDMAP_TX_CH_GET_CFG   0x1206
- TISCI_MSG_RM_UDMAP_RX_CH_GET_CFG   0x1216
- TISCI_MSG_RM_UDMAP_FLOW_GET_CFG        0x1232
- TISCI_MSG_RM_UDMAP_FLOW_SIZE_THRESH_GET_CFG    0x1233

There are no users in U-Boot for any of the above messages, So drop the
support for all the corresponding messages.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>