RISC-V: Add Types for Un-Typed zc Instructions

RISC-V: Add Types for Un-Typed zc Instructions

Adds types to the untyped zc instructions. Creates a new
types "pushpop" and "mvpair" for now

gcc/ChangeLog:

	* config/riscv/riscv.md: Add "pushpop" and "mvpair" types
	* config/riscv/zc.md: Update types

Signed-off-by: Edwin Lu <ewlu@rivosinc.com>