i2c: tegra: Add missing kernel-doc for dma_dev member

Fix the kernel-doc warning by describing the 'dma_dev' member in
the tegra_i2c_dev struct.  This resolves the compilation warning:

drivers/i2c/busses/i2c-tegra.c:297: warning: Function parameter or struct member 'dma_dev' not described in 'tegra_i2c_dev'

Signed-off-by: Hans Zhang <18255117159@163.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250522163814.399630-1-18255117159@163.com

Author: Hans Zhang

drivers/i2c/busses/i2c-tegra.c

@@ -253,6 +253,7 @@ struct tegra_i2c_hw_feature {
  * @dma_phys: handle to DMA resources
  * @dma_buf: pointer to allocated DMA buffer
  * @dma_buf_size: DMA buffer size
+ * @dma_dev: DMA device used for transfers
  * @dma_mode: indicates active DMA transfer
  * @dma_complete: DMA completion notifier
  * @atomic_mode: indicates active atomic transfer