BugLink: http://bugs.launchpad.net/bugs/1711056

Move the CONFIG_BNXT settings from the driver's Makefile to a dedicated
Kconfig file.
Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>