drm/amd/display: Move dml2_destroy to non-FPU compilation unit

drm/amd/display: Move dml2_destroy to non-FPU compilation unit

On PREEMPT_RT kernels, vfree() can sleep because spin_lock is
converted to rt_mutex. dml2_destroy() calls vfree() while inside
an FPU-guarded region (preempt_count=2), which is illegal.

dml2_wrapper_fpu.c is compiled with CC_FLAGS_FPU which defines
_LINUX_FPU_COMPILATION_UNIT, making DC_RUN_WITH_PREEMPTION_ENABLED()
resolve to a no-op. This prevents the macro from cycling FPU
context off/on around vfree().

Move dml2_destroy() to dml2_wrapper.c (non-FPU compilation unit)
where DC_RUN_WITH_PREEMPTION_ENABLED() properly cycles DC_FP_END/
DC_FP_START around vfree(). This pairs it with dml2_allocate_memory()
which already lives there.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Rafal Ostrowski <rafal.ostrowski@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>