riscv: dts: microchip: add icicle kit with production device

riscv: dts: microchip: add icicle kit with production device

With the introduction of the Icicle Kit using the production MPFS250T
device, it's necessary to distinguish it from the engineering sample
(-es) variant. Engineering samples cannot write to flash from the MSS,
as noted in the PolarFire SoC FPGA ES errata.

Add a new device tree (mpfs-icicle-kit-prod.dts) for the production
board which includes the icicle kit common dtsi and enable the system
controller SPI flash, which is only accessible on production silicon.

Remove redundant board compatible from fabric dtsi and update board
compatibles for v2025.07 release, which includes Mi-V IHC v2 for AMP
cluster communication.

Signed-off-by: Valentina Fernandez <valentina.fernandezalanis@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>