Reformat GD32 DMX source & update year

Apply extensive code style and formatting changes to GD32 DMX implementation: adjust brace placement, compress enums/structs to single-line forms, normalize spacing, and reformat IRQ/handler functions for consistency. Remove the "-fprefetch-loop-arrays" GCC pragma and update copyright year to 2026. Also minor whitespace/endif comment tweaks in dmxconst.h. These edits are intended to be non-functional refactors; no logic changes are expected, though removal of the pragma may affect compiler optimizations.

Author: vanvught

lib-dmx/include/dmxconst.h

@@ -60,8 +60,8 @@ inline constexpr uint32_t kMabTimeMin = 12;                                  ///
 inline constexpr uint32_t kMabTimeMax = 1000000;                             ///< 1s
 inline constexpr uint32_t kRefreshRateDefault = 40;                          ///< 40 Hz
 inline constexpr uint32_t kPeriodDefault = (1000000U / kRefreshRateDefault); ///< 25000 us
-inline constexpr uint32_t kBreakToBreakTimeMin = 1204;                     ///< us
+inline constexpr uint32_t kBreakToBreakTimeMin = 1204;                       ///< us
 } // namespace transmit
 } // namespace dmx
 
-#endif  // DMXCONST_H_
+#endif // DMXCONST_H_