tty: vt: define a common enum for VESA blanking constants

There are currently two places with VESA blanking constants definitions:
fb.h and console.h. Extract/unify the two to a separate header (vesa.h).

Given the fb's is in an uapi header, create the common header in uapi
too.

Note that instead of macros, an enum (vesa_blank_mode) is created. But
the macros are kept too (they now expand to the enum constants), just in
case someone in userspace performs some #ifdeffery.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Helge Deller <deller@gmx.de> # parisc STI console
Link: https://lore.kernel.org/r/20240122110401.7289-33-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>