Disable execute and nonidempotent PMA features for 65x

Created by: JeanRochCoulon

By setting 0 in Execute and NonIdempotent PMA input parameter configuration, the two features are disabled and not checked by cva6. For information, the PMA features could be checked outside cva6 based on read, write and execute information provided on AXI (or future OBI) bus. See Risc-V specification for more information.