RISC-V: Adjust scalar_to_vec cost

RISC-V: Adjust scalar_to_vec cost

1. Introduce vector regmove new tune info.
2. Adjust scalar_to_vec cost in add_stmt_cost.

We will get optimal codegen after this patch with -march=rv64gcv_zvl256b:

	lui	a5,%hi(a)
	li	a4,19
	sb	a4,%lo(a)(a5)
	li	a0,0
	ret

Tested on both RV32/RV64 no regression, Ok for trunk ?

	PR target/113281

gcc/ChangeLog:

	* config/riscv/riscv-protos.h (struct regmove_vector_cost): New struct.
	(struct cpu_vector_cost): Add regmove struct.
	(get_vector_costs): Export as global.
	* config/riscv/riscv-vector-costs.cc (adjust_stmt_cost): Adjust scalar_to_vec cost.
	(costs::add_stmt_cost): Ditto.
	* config/riscv/riscv.cc (get_common_costs): Export global function.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/pr113209.c: Adapt test.
	* gcc.dg/vect/costmodel/riscv/rvv/pr113281-1.c: New test.
	* gcc.dg/vect/costmodel/riscv/rvv/pr113281-2.c: New test.