drm/amdgpu: optimize queue reset and stop logic for sdma_v5_2

This patch refactors the SDMA v5.2 queue reset and stop logic to improve
code readability, maintainability, and performance. The key changes include:

1. **Generalized `sdma_v5_2_gfx_stop` Function**:
   - Added an `inst_mask` parameter to allow stopping specific SDMA instances
     instead of all instances. This is useful for resetting individual queues.

2. **Simplified `sdma_v5_2_reset_queue` Function**:
   - Removed redundant loops and checks by directly using the `ring->me` field
     to identify the SDMA instance.
   - Reused the `sdma_v5_2_gfx_stop` function to stop the queue, reducing code
     duplication.

v1: The general coding style is to declare variables like "i" or "r" last. E.g. longest lines first and short lasts. (Chritian)

Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>