ALSA: lola - fix lola build

sound/pci/lola/Makefile was trying to build lola modules even
when PCI and SND_LOLA were not enabled, causing build errors:

ERROR: "snd_pcm_hw_constraint_step" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_period_elapsed" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_dma_alloc_pages" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_hw_constraint_integer" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_sgbuf_ops_page" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_set_ops" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_lib_free_pages" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_lib_ioctl" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_lib_malloc_pages" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_sgbuf_get_chunk_size" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_dma_free_pages" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_lib_preallocate_pages_for_all" [sound/pci/lola/snd-lola.ko] undefined!
ERROR: "snd_pcm_new" [sound/pci/lola/snd-lola.ko] undefined!

Fix the Makefile to build only when CONFIG_SND_LOLA is enabled.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>