Adding reset-init handler to enable 256 bit key.

Change-Id: I264977d732e9dfaff8c333634492898b0fea90bc

tcl/target/max32520.cfg

@@ -17,3 +17,13 @@ set FLASH_CLK 40
 set FLASH_OPTIONS 0x23
 
 source [find target/max32xxx.cfg]
+
+proc max32520_aes256_reset_init {} {
+    # Enable encryption and 256 bit key
+    mww 0x40000000 0x320002
+}
+
+# Create custom reset sequence to set the AES keysize
+if { [expr $FLASH_OPTIONS & 0x40] } {
+    $_CHIPNAME.cpu configure -event reset-init { max32520_aes256_reset_init }
+}