[ALSA] sound: fix incorrect use of platform_device_register()

The platform_device allocated by platform_device_alloc()
should be added to the device hierarchy by platform_device_add()
instead of platform_device_register().
Otherwise it will hit WARN_ON() in platform_device_register().
by illegal refcount.
This patch fixes such incorrect usages in portman2x4 and mts64 drivers.
Also it removes unnecessary trailing whitespaces.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>