Revert "Rename DriveInfo.onerror to on_write_error" (fix mismerge)

Part of the first patch of the -drive rerror series has been merged once more
on top of the rest of the series. This effectively disables the rerror option
and always goes with the default value. Reverting the commit re-enables the
option.

This reverts commit fc072ec4.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

vl.c

@@ -2044,10 +2044,6 @@ BlockInterfaceErrorAction drive_get_on_error(
 {
     DriveInfo *dinfo;
 
-    if (is_read) {
-        return BLOCK_ERR_REPORT;
-    }
-
     QTAILQ_FOREACH(dinfo, &drives, next) {
         if (dinfo->bdrv == bdrv)
             return is_read ? dinfo->on_read_error : dinfo->on_write_error;