wilc1000: Fix missing newline in error message

Add missing newline in pr_err() message.

Signed-off-by: David Mosberger-Tang <davidm@egauge.net>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20211206232709.3192856-3-davidm@egauge.net