armv8: enable the SHA-3 extension the ML-KEM assembly needs

The ARM64 ML-KEM port emits eor3, which is not in the base ARMv8-A a toolchain
may be invoked with, and the file carries no directive:

  armv8-mlkem-asm.S: Error: selected processor does not support
                            `eor3 v31.16b,v0.16b,v5.16b,v10.16b'

The directive sits inside WOLFSSL_ARMASM_CRYPTO_SHA3, the guard selecting the
variant that needs it, so a build that has not opted in never asks for it.

The same file's sqrdmlsh deliberately gets none. RDMA is opt-out
(WOLFSSL_AARCH64_NO_SQRDMLSH) where SHA-3 is opt-in, and on a target with no
way to read the ID registers cpuid.c reports it present whenever that macro is
unset. A directive there would turn a build the assembler correctly rejects
into an image that traps on the first sqrdmlsh, so the mnemonic is left to
answer to -mcpu.

wolfcrypt/src/port/arm/armv8-mlkem-asm.S

@@ -9765,6 +9765,7 @@ L_sha3_aarch64_r:
 	.quad	0x8000000080008081,0x8000000000008080
 	.quad	0x0000000080000001,0x8000000080008008
 #ifdef WOLFSSL_ARMASM_CRYPTO_SHA3
+.arch_extension sha3
 #ifndef __APPLE__
 .text
 .globl	mlkem_sha3_blocksx3_crypto

wolfcrypt/src/port/arm/armv8-mlkem-asm.asm

@@ -9216,6 +9216,7 @@ L_sha3_aarch64_r
 	DCQ	0x8000000080008081, 0x8000000000008080
 	DCQ	0x0000000080000001, 0x8000000080008008
 	IF :DEF:WOLFSSL_ARMASM_CRYPTO_SHA3
+; .arch_extension sha3
 	AREA	|.text|, CODE, READONLY
 	ALIGN	4
 	EXPORT	mlkem_sha3_blocksx3_crypto

wolfcrypt/src/port/arm/armv8-mlkem-asm_c.c

@@ -9124,6 +9124,7 @@ void mlkem_sha3_blocksx3_crypto(word64* state)
 {
     const word64* r = L_sha3_aarch64_r;
     __asm__ __volatile__ (
+    ".arch_extension sha3\n\t"
         "stp	x29, x30, [sp, #-64]!\n\t"
         "add	x29, sp, #0\n\t"
         "str	%x[state], [x29, #40]\n\t"
@@ -9423,6 +9424,7 @@ void mlkem_shake128_blocksx3_seed_crypto(word64* state, byte* seed)
 {
     const word64* r = L_sha3_aarch64_r;
     __asm__ __volatile__ (
+    ".arch_extension sha3\n\t"
         "stp	x29, x30, [sp, #-64]!\n\t"
         "add	x29, sp, #0\n\t"
         "str	%x[state], [x29, #40]\n\t"
@@ -9744,6 +9746,7 @@ void mlkem_shake256_blocksx3_seed_crypto(word64* state, byte* seed)
 {
     const word64* r = L_sha3_aarch64_r;
     __asm__ __volatile__ (
+    ".arch_extension sha3\n\t"
         "stp	x29, x30, [sp, #-64]!\n\t"
         "add	x29, sp, #0\n\t"
         "str	%x[state], [x29, #40]\n\t"