Documentation: sound/cards: fix heading underline lengths for https: changes

Documentation: sound/cards: fix heading underline lengths for https: changes

Fix documentation build warnings for underline length too short,
caused by s/http/https/ and not changing the accompanying underlines.

Documentation/sound/cards/audigy-mixer.rst:335: WARNING: Title underline too short.
US Patents (https://www.uspto.gov/)
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Documentation/sound/cards/sb-live-mixer.rst:340: WARNING: Title underline too short.
US Patents (https://www.uspto.gov/)
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Fixes: 7ed33ea6b4fa ("ALSA: Replace HTTP links with HTTPS ones")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alexander A. Klimov <grandmaster@al2klimov.de>
Link: https://lore.kernel.org/r/357ee576-32a2-6e2b-1db6-78be39253846@infradead.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>