ALSA: hda - explicitly set buffer-align flag for Nvidia controllers

It turned out that Nvidial (HDMI) controllers require the buffer
alignment.  Thus it's better to mark it requiring the alignment, so that
we can switch to non-aligned behavior as default in future.

Also, change the module paramter to be bint, in order to let user
overriding the default value.

Signed-off-by: Takashi Iwai <tiwai@suse.de>