net: Make NETCONSOLE_DYNAMIC depend on CONFIGFS_FS

This patch fixes the following kconfig error after changing
CONFIGFS_FS -> select SYSFS:

fs/sysfs/Kconfig:1:error: recursive dependency detected!
fs/sysfs/Kconfig:1:	symbol SYSFS is selected by CONFIGFS_FS
fs/configfs/Kconfig:1:	symbol CONFIGFS_FS is selected by NETCONSOLE_DYNAMIC
drivers/net/Kconfig:3390:	symbol NETCONSOLE_DYNAMIC depends on SYSFS

Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: James Bottomley <James.Bottomley@suse.de>