Documentation: networking: device drivers: Remove stray asterisks

These asterisks were once references to a line that said:
  "* Other names and brands may be claimed as the property of others."
But now, they serve no purpose; they can only irritate the reader.

Fixes: f12a84a9 ("Documentation: fm10k: Add kernel documentation")
Fixes: 1e06edcc ("Documentation: i40e: Prepare documentation for RST conversion")
Fixes: 1fae869b ("Documentation: ice: Prepare documentation for RST conversion")
Fixes: df69ba43 ("ionic: Add basic framework for IONIC Network device driver")
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Acked-by: Shannon Nelson <snelson@pensando.io>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>