igc: Remove unused igc_acquire/release_nvm

igc_acquire_nvm() and igc_release_nvm() were added in 2018 as part of
commit ab405612 ("igc: Add NVM support")

but never used.

Remove them.

The igc_1225.c has it's own specific implementations.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20250102174142.200700-2-linux@treblig.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>