Add support for get_eeprom and get_eeprom_len ethtool ops

Specification states that PF software accesses NVM (shadow-ram) via AQ
commands (e.g. NVM Read, NVM Write) in the range 0x000000-0x00FFFF (64KB),
so the get_eeprom_len op should return 64KB.  If additional regions of the
16MB NVM must be read, another access method must be used.

The ethtool kernel code, by default, will ask for multiple page-size hunks
of the NVM not to exceed the value returned by ice_get_eeprom_len().
ice_read_sr_buf() deals with arch page sizes different than 4KB.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>