Update docs/porting/psa/spm.md

Co-Authored-By: danny4478 <[email protected]>

Author: Alexander Zilberkant

docs/porting/psa/spm.md

@@ -215,7 +215,7 @@ These are the guidelines you should follow if you have multicore systems:
 Target specific code of silicon partners who wish to have SPM capabilities must:
 
 - Implement a list of functions which are being called by SPM code.
-- Call other functions supplied by ARM.
+- Call Arm callback functions declared and documented in the HAL header files.
 
 The HAL can be logically divided into two different fields: