drm/amdgpu: remove set but not used variable 'count'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/amd/amdkfd/kfd_device.c: In function
‘kgd2kfd_post_reset’:
drivers/gpu/drm/amd/amdkfd/kfd_device.c:745:11: warning:
variable ‘count’ set but not used [-Wunused-but-set-variable]

'count' is never used, so can be removed. Thus 'atomic_dec_return'
can be replaced as 'atomic_dec'

Fixes: e42051d2 ("drm/amdkfd: Implement GPU reset handlers in KFD")
Signed-off-by: yu kuai <yukuai3@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_device.c

@@ -742,7 +742,7 @@ int kgd2kfd_pre_reset(struct kfd_dev *kfd)
 
 int kgd2kfd_post_reset(struct kfd_dev *kfd)
 {
-	int ret, count;
+	int ret;
 
 	if (!kfd->init_complete)
 		return 0;
@@ -750,7 +750,7 @@ int kgd2kfd_post_reset(struct kfd_dev *kfd)
 	ret = kfd_resume(kfd);
 	if (ret)
 		return ret;
-	count = atomic_dec_return(&kfd_locked);
+	atomic_dec(&kfd_locked);
 
 	atomic_set(&kfd->sram_ecc_flag, 0);