sdstrategy() shouldn't use values in disklabel until SDEV_MEDIA_LOADED is checked.  Fixes crash during boot when a device has no media loaded. e.g. a usb card reader with empty slots. From NetBSD. Problem was introduced by last commit to allow RAW_PART+S_IFCHAR opens to always succeed.
sdstrategy() shouldn't use values in disklabel until SDEV_MEDIA_LOADED
is checked.  Fixes crash during boot when a device has no media
loaded. e.g. a usb card reader with empty slots. From NetBSD. Problem
was introduced by last commit to allow RAW_PART+S_IFCHAR opens to
always succeed.

ok millert@ marco@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars