perf(w3ddevice): Optimize tile RGB data access and add null check

[seer-by-sentry]

Fixes CLIENT-2Z9. The issue was that: Uninitialized TileData internal member m_tileData causes null pointer dereference during texture update.

• Moved the call to getRGBDataForWidth outside the inner loop to prevent redundant function calls.
• Added a null check for the returned RGB data pointer to improve robustness.

This fix was generated by Seer in Sentry, triggered automatically. 👁️ Run ID: 12723206

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