bnxt_en: Fix compile error without CONFIG_RFS_ACCEL

Fix the following compile error:

.../bnxt.c: In function 'bnxt_cfg_ntp_filters':
.../bnxt.c:14077:37: error: implicit declaration of function 'rps_may_expire_flow' [-Werror=implicit-function-declaration]
14077 |                                 if (rps_may_expire_flow(bp->dev, fltr->base.rxq,
      |                                     ^~~~~~~~~~~~~~~~~~~

bnxt_cfg_ntp_filters() is only used when CONFIG_RFS_ACCEL is enabled.
User configured ntuple filters are directly added and will not go through
this function.  Wrap the body of bnxt_cfg_ntp_filters() with
CONFIG_RFS_ACCEL.

Fixes: 59cde76f

 ("bnxt_en: Refactor filter insertion logic in bnxt_rx_flow_steer().")
Reported-by: Arnd Bergmann <arnd@kernel.org>
Link: https://lore.kernel.org/netdev/20240103102332.3642417-1-arnd@kernel.org/
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>