drm/amd/amdgpu: Ensure isp_kernel_buffer_alloc() creates a new BO

When the BO pointer provided to amdgpu_bo_create_kernel() points to
non-NULL, amdgpu_bo_create_kernel() takes it as a hint to pin that address
rather than allocate a new BO.

This functionality is never desired for allocating ISP buffers. A new BO
should always be created when isp_kernel_buffer_alloc() is called, per the
description for isp_kernel_buffer_alloc().

Ensure this by zeroing *bo right before the amdgpu_bo_create_kernel() call.

Fixes: 55d42f6 ("drm/amd/amdgpu: Add helper functions for isp buffers")
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Pratap Nirujogi <pratap.nirujogi@amd.com>
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 73c8c29)

Author: kerneltoast

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

@@ -280,6 +280,8 @@ int isp_kernel_buffer_alloc(struct device *dev, u64 size,
 	if (ret)
 		return ret;
 
+	/* Ensure *bo is NULL so a new BO will be created */
+	*bo = NULL;
 	ret = amdgpu_bo_create_kernel(adev,
 				      size,
 				      ISP_MC_ADDR_ALIGN,