target/riscv: Move Zhinx* extensions on ISA string

target/riscv: Move Zhinx* extensions on ISA string

This commit moves ISA string conversion for Zhinx and Zhinxmin extensions.
Because extension category ordering of "H" is going to be after "V",
their ordering is going to be valid (on canonical order).

Signed-off-by: Tsukasa OI <research_trasio@irq.a4lg.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <7a988aedb249b6709f9ce5464ff359b60958ca54.1652181972.git.research_trasio@irq.a4lg.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>