aha1542: Merge aha1542_host_reset and aha1542_bus_reset

aha1542_host_reset and aha1542_bus_reset are almost same, merge them
into aha1542_reset

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>