removed unused #include <version.h>

The drivers below do not use LINUX_VERSION_CODE nor KERNEL_VERSION.
  drivers/char/pcmcia/ipwireless/tty.c
  drivers/char/synclink_gt.c
  drivers/char/xilinx_hwicap/xilinx_hwicap.c

This patch removes the said #include <version.h>.

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>