feat(dmamap): add DmaMap::sync method

[Koichi98]

Description

This PR completes the DMA mapping layer by adding synchronization operations for bounce buffers and cache coherency, plus integration with pre-allocated DMA pools.

DMA Synchronization (sync method)

• Bounce buffer synchronization: Automatically copies data between original buffers and bounce buffers at the right timing
  • PreWrite: Copies from original to bounce buffer before device writes
  • PostRead: Copies from bounce buffer to original after device reads
• Cache coherency placeholders: Framework for cache invalidation/flush operations on non-coherent architectures (currently uses memory barriers only)
• Architecture-specific handling: Prepared for RISC-V and AArch64 cache operations

Design Decisions

Deferred cache operations:
The current implementation uses memory barriers as a placeholder for full cache management. While sufficient for cache-coherent systems (like most x86_64), proper cache invalidation/flush operations are needed for non-coherent architectures. The TODO comments mark where architecture-specific cache operations should be added when non-coherent device support is required.

Related links

bus_dmamap_sync
https://github.com/openbsd/src/blob/95647c95e86787fd3d10394754ce3752dc75799c/sys/arch/amd64/amd64/bus_dma.c#L515

How was this PR tested?

Notes for reviewers