[TF-M] Partition log write UART without validation of permissions.

Hi all,

I noticed that partition log subsystem uses stdio_output_string through following chain of calls tfm_hal_output_sp_log => SVC TFM_SVC_OUTPUT_UNPRIV_STRING => tfm_hal_output_spm_log => stdio_output_string. SVC handler doesn't validate arguments, so it's allows APP RoT partitions to access PSA RoT memory via partition log subsystem. It seems that tfm_hal_memory_check must be called on SVC handler to validate permissions.

Best Regards, Roman.