snps: nsim: arc_v: update RMX100 hardware configuration

Update the hardware configuration for the Synopsys nSIM ARC-V RMX100:

- Change CLINT base address from 0x2000000 to 0xa0010000. The CLINT
  is now created by default in the RMX100 configuration, with its
  MMIO base already configured to use this address.

- Update nSIM MMIO base address to 2560 to align with the new memory
  map requirements.

- Remove PLIC support as the ARC-V RMX architecture only supports
  APLIC (Advanced Platform-Level Interrupt Controller), not PLIC.
  Note that APLIC support is not yet available in Zephyr, so
  interrupt controller functionality will be limited until APLIC
  is implemented.

- Replace legacy MPU configuration with PMP (Physical Memory Protection):
  Remove mpu_version, mpu_regions, and mpu_granule properties and add
  ARCV_PMP interface with 16 regions and granule=1. The MPU options
  were legacy and PMP is the standard RISC-V memory protection mechanism.

These changes align with the latest ARC-V RMX100 hardware memory map
and architectural requirements.

Signed-off-by: Afonso Oliveira <afonsoo@synopsys.com>