sparc: Fix tty compile warnings.

This patch fixes tty compile warnings as sugested by Alan Cox:

CC drivers/char/n_tty.o
drivers/char/n_tty.c: In function ‘normal_poll’:
drivers/char/n_tty.c:1555: warning: array subscript is above array bounds
drivers/char/n_tty.c:1564: warning: array subscript is above array bounds
drivers/char/n_tty.c: In function ‘read_chan’:
drivers/char/n_tty.c:1269: warning: array subscript is above array bounds
CC drivers/char/tty_ioctl.o
drivers/char/tty_ioctl.c: In function ‘set_termios’:
drivers/char/tty_ioctl.c:533: warning: array subscript is above array 
bounds
drivers/char/tty_ioctl.c:537: warning: array subscript is above array 
bounds
drivers/char/tty_ioctl.c: In function ‘tty_mode_ioctl’:
drivers/char/tty_ioctl.c:662: warning: array subscript is above array 
bounds
drivers/char/tty_ioctl.c:892: warning: array subscript is above array 
bounds
drivers/char/tty_ioctl.c:896: warning: array subscript is above array 
bounds
drivers/char/tty_ioctl.c:577: warning: array subscript is above array 
bounds
drivers/char/tty_ioctl.c:928: warning: array subscript is above array 
bounds
drivers/char/tty_ioctl.c:934: warning: array subscript is above array 
bounds

Signed-off-by: Robert Reif <reif@earthlink.net>
Signed-off-by: David S. Miller <davem@davemloft.net>