Realtek switch SoC docs

longan feature RSPAN

Registers

Offset Name Summary
RSPAN
d27c MIR_RSPAN_VLAN_CTRL
d28c MIR_RSPAN_TX_CTRL
d290 MIR_RSPAN_RX_TAG_RM_CTRL
d294 DMY_REG4_PKT_ENCAP
d298 DMY_REG5_PKT_ENCAP