igc: Remove unused igc_read/write_pci_cfg wrappers

igc_read_pci_cfg() and igc_write_pci_cfg were added in 2018 as part of
commit 146740f9 ("igc: Add support for PF")
but have remained unused.

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20250102174142.200700-3-linux@treblig.org


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