nrf_security: cracen: Use a smaller prng_pool on 54h20

The CPU that uses CRACEN on 54h20 has only 29kB of RAM so for this
platform we would like to save 96 bytes of RAM at the cost of PRNG
runtime.

Ref: NCSDK-NONE

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>

Author: SebastianBoe

subsys/nrf_security/src/drivers/cracen/cracenpsa/src/prng_pool.c

@@ -17,8 +17,14 @@
  * and can be freely adjusted later when we test this
  * in practice.
  *
+ * The CONFIG_SOC_NRF54H20_CPUSEC secure element only has 29kB of RAM
+ * so we have a smaller pool for this platform.
  */
+#ifdef CONFIG_SOC_NRF54H20_CPUSEC
+#define PRNG_POOL_SIZE (8)
+#else
 #define PRNG_POOL_SIZE (32)
+#endif
 
 static uint32_t prng_pool[PRNG_POOL_SIZE];
 static uint32_t prng_pool_remaining;