nfc: nci: constify several pointers to u8, sk_buff and other structs
Several functions receive pointers to u8, sk_buff or other structs but
do not modify the contents so make them const. This allows doing the
same for local variables and in total makes the code a little bit safer.
This makes const also data passed as "unsigned long opt" argument to
nci_request() function. Usual flow for such functions is:
1. Receive "u8 *" and store it (the pointer) in a structure
allocated on stack (e.g. struct nci_set_config_param),
2. Call nci_request() or __nci_request() passing a callback function an
the pointer to the structure via an "unsigned long opt",
3. nci_request() calls the callback which dereferences "unsigned long
opt" in a read-only way.
This converts all above paths to use proper pointer to const data, so
entire flow is safer.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>