ide/macio: fix wrong opaque with TRIM support

Commit 215e47b9 enabled TRIM by default, which revealed a bug in TRIM
support for the IDE macio emulation driver, introduced in d353fb72.

The call to dma_bdrv_io() is using a wrong opaque of type IDEState
instead of DBDMA_io. This patch fixes that.

Fixes LP#1179104

Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Tested-off-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>