ALSA: doc: Fix indentation warning

Fix a trivial warning for the indentation by putting an empty line:
  Documentation/sound/alsa-configuration.rst:2258: WARNING: Unexpected indentation.

Fixes: a39978e ("ALSA: doc: Add the description of quirk_flags option for snd-usb-audio")
Reported-by: Stephen Rothwell <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: tiwai

Documentation/sound/alsa-configuration.rst

@@ -2261,6 +2261,7 @@ delayed_register
 quirk_flags
     Contains the bit flags for various device specific workarounds.
     Applied to the corresponding card index.
+
         * bit 0: Skip reading sample rate for devices
         * bit 1: Create Media Controller API entries
         * bit 2: Allow alignment on audio sub-slot at transfer