RISC-V: Remove redundant codes of VLS patterns[NFC]

Consider those VLS patterns are the same VLA patterns.
Now extend VI -> V_VLSI and VF -> V_VLSF.
Then remove the redundant codes of VLS patterns.

gcc/ChangeLog:

	* config/riscv/autovec-vls.md (<optab><mode>3): Deleted.
	(copysign<mode>3): Ditto.
	(xorsign<mode>3): Ditto.
	(<optab><mode>2): Ditto.
	* config/riscv/autovec.md: Extend VLS modes.