crypto: Update HASH_MAX_DESCSIZE to include space for fallback tfm.

Adds additional 8 byte required for fallback tfm pointer in versal-sha3-384.
It fixes self-test warn_on when HMAC template tries to use versal-sha3-384
as inner tfm.

 -----------[ cut here ]-----------
 WARNING: CPU: 1 PID: 578 at crypto/shash.c:495 crypto_shash_init_tfm+0xac/0xd0
 Modules linked in:
 CPU: 1 PID: 578 Comm: cryptomgr_test Tainted: G        W          6.6.0-xilinx-v2024.1-g01dca40485e6-dirty #7
 Hardware name: Xilinx Versal vck190 Eval board revA (DT)
 pstate: 20000005 (nzCv daif PAN -UAO -TCO -DIT -SSBS BTYPE=-)
 pc : crypto_shash_init_tfm+0xac/0xd0

We can remove this fix once Herbert is done with updating shash framework
to support multibuffer requests (link below).

Signed-off-by: Harsh Jain <[email protected]>
Message-ID: <[email protected]>
Link: https://lore.kernel.org/linux-crypto/CAFXBA=kHUHNH_BEnK=sWvWPJPoxsDh56OEhisbRGzdD19Di2gQ@mail.gmail.com/T/#md4c42d52caab7c7dd8ee41ba194d2019d7e71d61
State: not-upstreamable

Author: harshj-xlnx

include/crypto/hash.h

@@ -180,10 +180,10 @@ struct shash_desc {
 #define HASH_MAX_DIGESTSIZE	 64
 
 /*
- * Worst case is hmac(sha3-224-generic).  Its context is a nested 'shash_desc'
- * containing a 'struct sha3_state'.
+ * Worst case is hmac(versal-sha3-384). Its context is a nested 'shash_desc'
+ * containing a 'struct sha3_state' plus fallback shash_desc.
  */
-#define HASH_MAX_DESCSIZE	(sizeof(struct shash_desc) + 360)
+#define HASH_MAX_DESCSIZE	((sizeof(struct shash_desc) * 2) + 360)
 
 #define SHASH_DESC_ON_STACK(shash, ctx)					     \
 	char __##shash##_desc[sizeof(struct shash_desc) + HASH_MAX_DESCSIZE] \