RISC-V: Support VLS floating-point FMA/FNMA/FMS auto-vectorization

Support VLS floating-point FMA/FNMA/FMS patterns.

Regression no difference after this patch, Committed.

gcc/ChangeLog:

	* config/riscv/autovec.md: Extend VLS floating-point modes.
	* config/riscv/vector.md: Ditto.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vls/def.h: Add FMS tests.
	* gcc.target/riscv/rvv/autovec/vls/fma-5.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fma-6.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fma-7.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fms-1.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fms-2.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fms-3.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fnma-5.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fnma-6.c: New test.
	* gcc.target/riscv/rvv/autovec/vls/fnma-7.c: New test.