ASoC: Blackfin: convert internal names from bf52x to bf5xx

These drivers aren't BF52x specific, so don't use bf52x in the names.

Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>