RISC-V: ICE for vlmul_ext_v intrinsic API

	PR target/109617

gcc/ChangeLog:

	* config/riscv/vector-iterators.md: Support VNx2HI and VNX4DI when MIN_VLEN >= 128.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/vlmul_ext-1.c: New test.

Signed-off-by: Yanzhang Wang <yanzhang.wang@intel.com>
Co-authored-by: Pan Li <pan2.li@intel.com>
Signed-off-by: Yanzhang Wang <yanzhang.wang@intel.com>