MAINTAINERS: TTY LAYER: add some ./include/linux/ header files

An early prototypical automated code analysis of headers and the
existing MAINTAINERS sections identified some header files in
./include/linux/ to be probably included into the TTY LAYER section.

I further checked those suggestions by this analysis and identified a
subset of files that I am rather certain to belong to the TTY LAYER.

Add these ./include/linux/ header files to TTY LAYER in MAINTAINERS.

The patterns include/linux/tty*.h and include/linux/vt_*.h currently cover:

include/linux/tty.h
include/linux/tty_driver.h
include/linux/tty_flip.h
include/linux/tty_ldisc.h

include/linux/vt_buffer.h
include/linux/vt_kern.h

Signed-off-by: Lukas Bulwahn <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

MAINTAINERS

···
 F:	Documentation/driver-api/serial/
 F:	drivers/tty/
 F:	drivers/tty/serial/serial_core.c
+F:	include/linux/selection.h
 F:	include/linux/serial.h
 F:	include/linux/serial_core.h
-F:	include/linux/tty.h
+F:	include/linux/sysrq.h
+F:	include/linux/tty*.h
+F:	include/linux/vt.h
+F:	include/linux/vt_*.h
 F:	include/uapi/linux/serial.h
 F:	include/uapi/linux/serial_core.h
 F:	include/uapi/linux/tty.h