include/sysemu/blockdev.h: remove drive_mark_claimed_by_board and inline drive_def

drive_def is only a particular use case of
qemu_opts_parse_noisily, so it can be inlined.

Also remove drive_mark_claimed_by_board, as it is only defined
but not implemented (nor used) anywhere.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20211215121140.456939-3-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>