os/board/rtl8730e: Integrate LCD with PM

[edwakuwaku]

• Implement logic for LCD operation under different PM states
• Reinit both MIPI and LCDC when wakeup from power saving
• Remove redundant code and cleanup
• Fix some code misalignment

[edwakuwaku]

This PR is tested with lcd example. LCD is working fine after wakeup from PG sleep.