drm/amdgpu: fix off by one in amdgpu_gfx_kiq_acquire()

stable inclusion
from stable-v5.10.111
commit 0c122eb3a109356fb2c39f49c1768321248d0f1d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5GL1Z

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0c122eb3a109356fb2c39f49c1768321248d0f1d

--------------------------------

[ Upstream commit 1647b54e ]

This post-op should be a pre-op so that we do not pass -1 as the bit
number to test_bit().  The current code will loop downwards from 63 to
-1.  After changing to a pre-op, it loops from 63 to 0.

Fixes: 71c37505 ("drm/amdgpu/gfx: move more common KIQ code to amdgpu_gfx.c")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c

@@ -263,7 +263,7 @@ static int amdgpu_gfx_kiq_acquire(struct amdgpu_device *adev,
 		    * adev->gfx.mec.num_pipe_per_mec
 		    * adev->gfx.mec.num_queue_per_pipe;
 
-	while (queue_bit-- >= 0) {
+	while (--queue_bit >= 0) {
 		if (test_bit(queue_bit, adev->gfx.mec.queue_bitmap))
 			continue;