amiserial: Remove unused variable icount

drivers/char/amiserial.c: In function ?rs_ioctl?:
drivers/char/amiserial.c:1302: warning: unused variable ?icount?

commit 0587102c ("tty: icount changeover for
other main devices") removed the users, but not the actual variable.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>