caif: reduce stack size, again

caif: reduce stack size, again

I tried to fix the stack usage in this function a couple of years ago,
but there is still a problem with the latest gcc versions in some
configurations:

net/caif/cfctrl.c:553:1: error: the frame size of 1296 bytes is larger than 1280 bytes [-Werror=frame-larger-than=]

Reduce this once again, with a separate cfctrl_link_setup() function that
holds the bulk of all the local variables. It also turns out that the
param[] array that takes up a large portion of the stack is write-only
and can be left out here.

Fixes: ce6289661b14 ("caif: reduce stack size with KASAN")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20250620112244.3425554-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>