wifi: rtw89: pci: use RDU status of R_BE_PCIE_DMA_IMR_0_V1 instead for 8922DE

wifi: rtw89: pci: use RDU status of R_BE_PCIE_DMA_IMR_0_V1 instead for 8922DE

The original RDU status of R_BE_HAXI_HIMR00 needs additional IO to get
the status. The new WiFi 7 8922DE add the status to R_BE_PCIE_DMA_IMR_0_V1
which is read already, so we can reduce one reading IO.

After the changes, interrupt behavior of RTL8922DE in low power mode is
the same as normal mode, so remove the configuration function for low
power mode.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250826085152.28164-4-pkshih@realtek.com