iwlwifi: dbg_ini: Split memcpy() to avoid multi-field write

To avoid a run-time false positive in the stricter FORTIFY_SOURCE
memcpy() checks, split the memcpy() into the struct and the data.
Additionally switch the data member to a flexible array to follow
modern language conventions.

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210727205855.411487-64-keescook@chromium.org


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>