idpf: fix mismatched free function for dma_alloc_coherent

idpf: fix mismatched free function for dma_alloc_coherent

The mailbox receive path allocates coherent DMA memory with
dma_alloc_coherent(), but frees it with dmam_free_coherent().
This is incorrect since dmam_free_coherent() is only valid for
buffers allocated with dmam_alloc_coherent().

Fix the mismatch by using dma_free_coherent() instead of
dmam_free_coherent

Fixes: e54232da1238 ("idpf: refactor idpf_recv_mb_msg")
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Madhu Chittim <madhu.chittim@intel.com>
Link: https://patch.msgid.link/20250925180212.415093-1-alok.a.tiwari@oracle.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>