i40e: reduce stack usage in i40e_set_fc

The functions i40e_aq_get_phy_abilities_resp() and i40e_set_fc() both
have giant structure on the stack, which makes each one use stack frames
larger than 500 bytes.

As clang decides one function into the other, we get a warning for
exceeding the frame size limit on 32-bit architectures:

drivers/net/ethernet/intel/i40e/i40e_common.c:1654:23: error: stack frame size of 1116 bytes in function 'i40e_set_fc' [-Werror,-Wframe-larger-than=]

When building with gcc, the inlining does not happen, but i40e_set_fc()
calls i40e_aq_get_phy_abilities_resp() anyway, so they add up on the
kernel stack just as much.

The parts that actually use large stacks don't overlap, so make sure
each one is a separate function, and mark them as noinline_for_stack to
prevent the compilers from combining them again.

Fixes: 0a862b43

 ("i40e/i40evf: Add module_types and update_link_info")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>