ALSA: hda - Fix buffer-alignment regression with Nvidia HDMI

The commit 2ae66c26


    ALSA: hda: option to enable arbitrary buffer/period sizes
introduced a regression on machines with Intel controller and Nvidia
HDMI.  The reason is that the driver modifies the global variable
align_buffer_size when an Intel controller is found, and the Nvidia
HDMI controller is probed after Intel although Nvidia chips require
the aligned buffers.

This patch fixes the problem by moving the flag into the local struct
so that it's not affected by other controllers.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=42567

Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>