net: mana: Fix build errors when CONFIG_NET_SHAPER is disabled

Fix build errors when CONFIG_NET_SHAPER is disabled, including:

drivers/net/ethernet/microsoft/mana/mana_en.c:804:10: error:
'const struct net_device_ops' has no member named 'net_shaper_ops'

804 | .net_shaper_ops = &mana_shaper_ops,

drivers/net/ethernet/microsoft/mana/mana_en.c:804:35: error:
initialization of 'int (*)(struct net_device *, struct neigh_parms *)'
from incompatible pointer type 'const struct net_shaper_ops *'
[-Werror=incompatible-pointer-types]

804 | .net_shaper_ops = &mana_shaper_ops,

Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
Fixes: 75cabb46935b ("net: mana: Add support for net_shaper_ops")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202506230625.bfUlqb8o-lkp@intel.com/
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/1750851355-8067-1-git-send-email-ernis@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>