Fix CMAC heap pointer reference in wc_CmacFree() and wc_CMAC_Grow()

Issue

The wc_CmacFree() function was attempting to access cmac->heap which does not exist in the Cmac structure, thus causing a compile failure. Additionally, wc_CMAC_Grow() was passing NULL for the heap parameter, creating an pointer mismatch if the heap is non NULL. The Cmac structure contains an Aes member, and it is the Aes structure that has the heap field.

How to Reproduce

./autogen.sh
./configure --enable-cmac CFLAGS="-DWOLFSSL_HASH_KEEP"
make

Context: How heap is initialized

In wc_InitCmac_ex() (line 149: cmac.c), the heap parameter is passed to wc_AesInit():

ret = wc_AesInit(&cmac->aes, heap, devId);

This stores the heap pointer in cmac->aes.heap. So when allocating/freeing CMAC memory, we should use cmac->aes.heap to ensure we're using the same heap pointer throughout the CMAC lifecycle.

Fix

Two changes in wolfcrypt/src/cmac.c:

1. Line 74 - wc_CMAC_Grow(): Changed NULL to cmac->aes.heap when calling _wc_Hash_Grow() to ensure allocation uses the correct heap
2. Line 260 - wc_CmacFree(): Changed cmac->heap to cmac->aes.heap to use the correct heap pointer for deallocation