The UEFI framebuffer driver vt_efifb requires vt(4), so add a
mechanism for the startup routine to set the preferred console.
This change is ugly because console init happens very early in the
boot, making a cleaner interface difficult. This change is intended
only to facilitate the sc(4) / vt(4) transition, and can be reverted
once vt(4) is the default.
r268160: Fix typos in VTY constant names from r268158
r268982: Don't pass null kmdp to preload_search_info