rsi: remove unused including <linux/version.h>

Fix the following versioncheck warning:
./drivers/net/wireless/rsi/rsi_91x_ps.c: 19 linux/version.h not needed.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>