RISC-V: Add Andes 25 series pipeline description.

RISC-V: Add Andes 25 series pipeline description.

gcc/ChangeLog:

	* config/riscv/andes-25-series.md: New file.
	* config/riscv/riscv-cores.def (RISCV_TUNE): Add andes-25-series.
	(RISCV_CORE): Add Andes 25-series cpu list.
	* config/riscv/riscv-opts.h
	(enum riscv_microarchitecture_type): Add andes_25_series_.
	* config/riscv/riscv.cc: Add andes_25_tune_info.
	* config/riscv/riscv.md: Add andes_25.
	* doc/riscv-mcpu.texi: Regenerated for Andes cpu list.
	* doc/riscv-mtune.texi: Regenerated for andes-25-series.