bcma: extract SPROM rev 9 the same way as rev 8

SPROM rev 9 was discovered on 14e4:4331, it seems to have very similar
layout to rev 8 one. Use the same extracting function until we find some
differences.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>