staging: gdm72xx: fix block comment style

This patch fixes the following checkpatch warnings, which are issued
when the gdm72xx driver is moved out of staging into drivers/net/wimax:

  WARNING: networking block comments don't use an empty /* line, use /* Comment...
  WARNING: networking block comments start with * on subsequent lines
  WARNING: networking block comments put the trailing */ on a separate line

Signed-off-by: Ben Chan <benchan@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>