ice: cache NVM module bank information

The ice flash contains two copies of each of the NVM, Option ROM, and
Netlist modules. Each bank has a pointer word and a size word. In order
to correctly read from the active flash bank, the driver must calculate
the offset manually.

During NVM initialization, read the Shadow RAM control word and
determine which bank is active for each NVM module. Additionally, cache
the size and pointer values for use in calculating the correct offset.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>