userspace/dot-config: remove Kconfig_sfp_fiber.in

partly revert the commit:
70c80659

 Add Kconfig-sfp-fiber.in in dot-config

The file Kconfig_sfp_fiber.in is copied during the build from the repo's
root.

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>

userspace/dot-config/.gitignore

 Kconfig
 Kconfig_port_timing.in
+Kconfig_sfp_fiber.in
 Kconfig_vlans.in
 dot-config
 conf