watchdog/hardlockup: fix typo in config HARDLOCKUP_DETECTOR_PREFER_BUDDY

Commit a5fcc236 ("watchdog/hardlockup: make HAVE_NMI_WATCHDOG
sparc64-specific") accidentially introduces a typo in one of the config
dependencies of HARDLOCKUP_DETECTOR_PREFER_BUDDY.

Fix this accidental typo.

Link: https://lkml.kernel.org/r/20230623040717.8645-1-lukas.bulwahn@gmail.com
Fixes: a5fcc236

 ("watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>