Crypto: Fix const-correctness in aead_test

Following a recent refactor, some buffers and pointers have
the wrong const attributes that need to be fixed

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: If1d97ee509e15fc591c48c4f7f7f88bd090207b8
diff --git a/tests_reg/test/secure_fw/suites/crypto/crypto_tests_common.c b/tests_reg/test/secure_fw/suites/crypto/crypto_tests_common.c
index 518e730..3718ab8 100644
--- a/tests_reg/test/secure_fw/suites/crypto/crypto_tests_common.c
+++ b/tests_reg/test/secure_fw/suites/crypto/crypto_tests_common.c
@@ -1765,10 +1765,11 @@
         "This is my plaintext message and it's made of 68 characters...!1234";
     const uint8_t associated_data[] =
         "This is my associated data to authenticate";
-    const uint8_t inline_buf[ENC_DEC_BUFFER_SIZE_AEAD] = {0};
+    uint8_t inline_buf[ENC_DEC_BUFFER_SIZE_AEAD] = {0};
     uint8_t decrypted_data[MAX_PLAIN_DATA_SIZE_AEAD] = {0};
     uint8_t encrypted_data[ENC_DEC_BUFFER_SIZE_AEAD] = {0};
-    uint8_t *input_buffer, *output_buffer;
+    const uint8_t *input_buffer;
+    uint8_t *output_buffer;
     size_t encrypted_data_length = 0, decrypted_data_length = 0;
     size_t total_output_length = 0, total_encrypted_length = 0;
     uint8_t *tag;