[PATCH V3] firmware: ti_sci: fix the secure_hdr in do_xfer

[Nishanth Menon]

On 18:37-20240124, Dhruva Gole wrote:
> The secure_hdr needs to be 0 init-ed however this was never being put
> into the secure_buf, leading to possibility of the first 4 bytes of
> secure_buf being possibly garbage.
> 
> Fix this by initialising the secure_hdr itself to the secure_buf
> location, thus when we make it 0, it automatically ensures the first 4
> bytes are 0.
> 
> Fixes: 32cd25128bd849 ("firmware: Add basic support for TI System Control Interface (TI SCI)")
> Signed-off-by: Dhruva Gole <d-gole at ti.com>
> ---
> 
> Boot tested for sanity on AM62x SK
> https://gist.github.com/DhruvaG2000/724ceba3a0db03f4b0bff47de1160074
> 
> Changelog:
> v2 --> v3
> Address Kamlesh's comment on v2: use sizeof(struct ti_sci_secure_msg_hdr)

Lets finish discussing in:
https://lore.kernel.org/all/20240124163910.sp7gt56lihoujm7k@etching/

Responding to keep patchworks happy.
-- 
Regards,
Nishanth Menon
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