drm/amd/display: Fix invalid context error in dml helper

[Why]
"BUG: sleeping function called from invalid context" error.
after:
"drm/amd/display: Protect FPU in dml2_validate()/dml21_validate()"

The populate_dml_plane_cfg_from_plane_state() uses the GFP_KERNEL flag
for memory allocation, which shouldn't be used in atomic contexts.

The allocation is needed only for using another helper function
get_scaler_data_for_plane().

[How]
Modify helpers to pass a pointer to scaler_data within existing context,
eliminating the need for dynamic memory allocation/deallocation
and copying.

Fixes: 366e77cd ("drm/amd/display: Protect FPU in dml2_validate()/dml21_validate()")
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit bd3e84bc)
Cc: stable@vger.kernel.org