hw/ide: Convert DeviceClass init to realize

hw/ide: Convert DeviceClass init to realize

Replace init with realize in IDEDeviceClass, which has errp
as a parameter. So all the implementations now use error_setg
instead of error_report for reporting error.

Cc: John Snow <jsnow@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>
Signed-off-by: Mao Zhongyi <maozy.fnst@cn.fujitsu.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: c4d27b4b5d9e37468e63e35214ce4833ca271542.1505737465.git.maozy.fnst@cn.fujitsu.com
Signed-off-by: John Snow <jsnow@redhat.com>