sha2

sha2: improve RISC-V Zknh backends #1204

Job	Run time
riscv32-zknh	1m 29s
riscv64-zknh	1m 45s
set-msrv / set-msrv	3s
minimal-versions / minimal-versions	39s
macos (1.79.0)	39s
build (1.79.0, thumbv7em-none-eabi)	6m 3s
linux (i686-unknown-linux-gnu, 1.79.0, sudo apt update && sudo apt install gcc-multilib)	1m 1s
macos (stable)	26s
cross (1.79.0, aarch64-unknown-linux-gnu, default)	20m 44s
build (1.79.0, wasm32-unknown-unknown)	21s
linux (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	57s
cross (1.79.0, powerpc-unknown-linux-gnu, default)	41s
build (1.79.0, loongarch64-unknown-linux-gnu)	19s
linux (x86_64-unknown-linux-gnu, 1.79.0)	48s
cross (stable, aarch64-unknown-linux-gnu, default)	36s
build (stable, thumbv7em-none-eabi)	16s
linux (x86_64-unknown-linux-gnu, stable)	36s
windows (1.79.0, x86_64-pc-windows-gnu)	57s
cross (stable, powerpc-unknown-linux-gnu, default)	12m 36s
windows (stable, x86_64-pc-windows-gnu)	10m 40s
build (stable, wasm32-unknown-unknown)	24s
build (stable, loongarch64-unknown-linux-gnu)	19s
	1h 2m 19s

Provide feedback