drm/amd/display: Use pre-allocated temp struct for bounding box update

[Why]

There is a theoretical problem in prior patches for reducing the stack
size of *update_bw_bounding_box() functions.

By modifying the soc.clock_limits[n] struct directly, this can cause
unintended behavior as the for loop attempts to swap rows in
clock_limits[n]. A temporary struct is still required to make sure we
stay functinoally equivalent.

[How]

Add a temporary clock_limits table to the SOC struct, and use it when
swapping rows.

Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>