ice: health.c: fix compilation on gcc 7.5

GCC 7 is not as good as GCC 8+ in telling what is a compile-time
const, and thus could be used for static storage.
Fortunately keeping strings as const arrays is enough to make old
gcc happy.

Excerpt from the report:
My GCC is: gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0.

  CC [M]  drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.o
drivers/net/ethernet/intel/ice/devlink/health.c:35:3: error: initializer element is not constant
   ice_common_port_solutions, {ice_port_number_label}},
   ^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/intel/ice/devlink/health.c:35:3: note: (near initialization for 'ice_health_status_lookup[0].solution')
drivers/net/ethernet/intel/ice/devlink/health.c:35:31: error: initializer element is not constant
   ice_common_port_solutions, {ice_port_number_label}},
                               ^~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/intel/ice/devlink/health.c:35:31: note: (near initialization for 'ice_health_status_lookup[0].data_label[0]')
drivers/net/ethernet/intel/ice/devlink/health.c:37:46: error: initializer element is not constant
   "Change or replace the module or cable.", {ice_port_number_label}},
                                              ^~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/intel/ice/devlink/health.c:37:46: note: (near initialization for 'ice_health_status_lookup[1].data_label[0]')
drivers/net/ethernet/intel/ice/devlink/health.c:39:3: error: initializer element is not constant
   ice_common_port_solutions, {ice_port_number_label}},
   ^~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 85d6164e ("ice: add fw and port health reporters")
Reported-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Closes: https://lore.kernel.org/netdev/CY8PR11MB7134BF7A46D71E50D25FA7A989F72@CY8PR11MB7134.namprd11.prod.outlook.com


Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Suggested-by: Simon Horman <horms@kernel.org>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Sunitha Mekala <sunithax.d.mekala@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>