w32: Fix access to host devices (regression)

w32: Fix access to host devices (regression)

QEMU failed to open host devices like \\.\PhysicalDrive0 (first hard disk)
since some time (commit 8a79380b8ef1b02d2abd705dd026a18863b09020?).

Those devices use hdev_open which did not use the latest API for options.
This resulted in a fatal runtime error:

  Block protocol 'host_device' doesn't support the option 'filename'

Duplicate code from raw_open to fix this.

Cc: [email protected]
Reported-by: David Brenner <[email protected]>
Signed-off-by: Stefan Weil <[email protected]>
Reviewed-by: Kevin Wolf <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>