ALSA: pcm: Protect call to dma_mmap_coherent() by check for HAS_DMA

If NO_DMA=y:

    sound/core/pcm_native.o: In function `snd_pcm_lib_default_mmap':
    pcm_native.c:(.text+0x144c): undefined reference to `bad_dma_ops'
    pcm_native.c:(.text+0x1474): undefined reference to `dma_common_mmap'

Add a check for HAS_DMA to fix this.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>