netfs: Rename CONFIG_FSCACHE_DEBUG to CONFIG_NETFS_DEBUG

CONFIG_FSCACHE_DEBUG should have been renamed to CONFIG_NETFS_DEBUG, so do
that now.

Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/1410796.1721333406@warthog.procyon.org.uk


cc: Uwe Kleine-König <ukleinek@kernel.org>
cc: Christian Brauner <brauner@kernel.org>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>