cachefiles: Allow cachefiles to actually function

Remove the block that allowed cachefiles to be compiled but prevented it
from actually starting a cache.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819649497.215744.2872504990762846767.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906956491.143852.4951522864793559189.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967165374.1823006.14248189932202373809.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021564379.640689.7921380491176827442.stgit@warthog.procyon.org.uk/ # v4