plfxlc: Remove unused include <linux/version.h>

Eliminate the follow versioncheck warning:

./drivers/net/wireless/purelifi/plfxlc/usb.c: 20 linux/version.h not
needed.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220429075459.72029-1-jiapeng.chong@linux.alibaba.com