ALSA: docs: Correct the kernel object suffix of target

The correct suffix is 'y' for the kernel code and
'objs' for the user space. Update documentation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240506085219.3403731-1-andriy.shevchenko@linux.intel.com


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