Allow tweaking PSA_KEY_SLOT_COUNT

Signed-off-by: Steven Cooreman <[email protected]>

ChangeLog.d/psa_allow_tweaking_library_configuration.txt

@@ -0,0 +1,5 @@
+Features
+   * The PSA crypto subsystem can now be configured to use less static RAM by
+     tweaking the setting for the maximum amount of keys simultaneously in RAM.
+     PSA_KEY_SLOT_COUNT sets the maximum number of volatile keys that can
+     exist simultaneously. It has a sensible default if not overridden.

library/psa_crypto_slot_management.h

@@ -27,7 +27,9 @@
 
 /* Number of key slots (plus one because 0 is not used).
  * The value is a compile-time constant for now, for simplicity. */
+#if !defined(PSA_KEY_SLOT_COUNT)
 #define PSA_KEY_SLOT_COUNT 32
+#endif
 
 /** Range of volatile key identifiers.
  *