crypto: powerpc/sha1 - remove unused temporary workspace

The PowerPC implementation of SHA-1 doesn't actually use the 16-word
temporary array that's passed to the assembly code.  This was probably
meant to correspond to the 'W' array that lib/sha1.c uses.  However, in
sha1-powerpc-asm.S these values are actually stored in GPRs 16-31.

Referencing SHA_WORKSPACE_WORDS from this code also isn't appropriate,
since it's an implementation detail of lib/sha1.c.

Therefore, just remove this unneeded array.

Tested with:

	export ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnu-
	make mpc85xx_defconfig
	cat >> .config << EOF
	# CONFIG_MODULES is not set
	# CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set
	CONFIG_DEBUG_KERNEL=y
	CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y
	CONFIG_CRYPTO_SHA1_PPC=y
	EOF
	make olddefconfig
	make -j32
	qemu-system-ppc -M mpc8544ds -cpu e500 -nographic \
		-kernel arch/powerpc/boot/zImage \
		-append "cryptomgr.fuzz_iterations=1000 cryptomgr.panic_on_fail=1"

Cc: linuxppc-dev@lists.ozlabs.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>