RISC-V: Fix incorrect mode tieable which cause ICE in RA[PR111296]

RISC-V: Fix incorrect mode tieable which cause ICE in RA[PR111296]

This patch fix incorrect mode tieable between DI and V2SI which cause ICE
in RA.

gcc/ChangeLog:

	PR target/111296
	* config/riscv/riscv.cc (riscv_modes_tieable_p): Fix incorrect mode
	tieable for RVV modes.

gcc/testsuite/ChangeLog:

	PR target/111296
	* g++.target/riscv/rvv/base/pr111296.C: New test.