CRYPTO: Octeon: Don't disable bottom half in octeon-md5

Don't disable bottom half while the crypto engine is in use, as it
should be unnecessary: All kernel crypto engine usage is wrapped with
crypto engine state save/restore, so if we get interrupted by softirq
that uses crypto they should save and restore our context.

This actually fixes an issue when running OCTEON MD5 with interrupts
disabled (tcrypt mode=302). There's a WARNING because the module is
trying to enable the bottom half with irqs disabled:

[   52.656610] ------------[ cut here ]------------
[   52.661439] WARNING: CPU: 1 PID: 428 at /home/aaro/git/linux/kernel/softirq.c:150 __local_bh_enable_ip+0x9c/0xd8()
[   52.671780] Modules linked in: tcrypt(+)
[...]
[   52.763539] [<ffffffff8114082c>] warn_slowpath_common+0x94/0xd8
[   52.769465] [<ffffffff81144614>] __local_bh_enable_ip+0x9c/0xd8
[   52.775390] [<ffffffff81119574>] octeon_md5_final+0x12c/0x1e8
[   52.781144] [<ffffffff81337050>] shash_compat_digest+0xd0/0x1b0
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9490/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/cavium-octeon/crypto/octeon-md5.c

@@ -97,7 +97,6 @@ static int octeon_md5_update(struct shash_desc *desc, const u8 *data,
 	memcpy((char *)mctx->block + (sizeof(mctx->block) - avail), data,
 	       avail);
 
-	local_bh_disable();
 	preempt_disable();
 	flags = octeon_crypto_enable(&state);
 	octeon_md5_store_hash(mctx);
@@ -115,7 +114,6 @@ static int octeon_md5_update(struct shash_desc *desc, const u8 *data,
 	octeon_md5_read_hash(mctx);
 	octeon_crypto_disable(&state, flags);
 	preempt_enable();
-	local_bh_enable();
 
 	memcpy(mctx->block, data, len);
 
@@ -133,7 +131,6 @@ static int octeon_md5_final(struct shash_desc *desc, u8 *out)
 
 	*p++ = 0x80;
 
-	local_bh_disable();
 	preempt_disable();
 	flags = octeon_crypto_enable(&state);
 	octeon_md5_store_hash(mctx);
@@ -153,7 +150,6 @@ static int octeon_md5_final(struct shash_desc *desc, u8 *out)
 	octeon_md5_read_hash(mctx);
 	octeon_crypto_disable(&state, flags);
 	preempt_enable();
-	local_bh_enable();
 
 	memcpy(out, mctx->hash, sizeof(mctx->hash));
 	memset(mctx, 0, sizeof(*mctx));