s390/3270: fix minor_start issue

s390/3270: fix minor_start issue

The 3270 device nodes 227/0 and 228/0 are special. 227/0 is never used,
and 228/0 is used to redirect full screen applications from /dev/3270/tub
to the real device node of the 3270 terminal.
To keep the device names /dev/3270/tty<x> consistent with the minor number
the device driver sets minor_start to 0 and skips minor 0. That makes the
tty index equivalent to the minor number. But doing so seems to causes
problems with init scripts.
A better solution is to set minor_start to the correct value of 1 and
set name_base to 1 as well. tty_register_device will then automatically
create the correct tty name.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>