vhost: remove VIRTIO_BLK_F_* feature bits from vhost_inernal.h

VIRTIO_BLK_F_* feature bits is defined by virtio_blk specification and
SPDK already has a copy of the system file header <linux/virtio_blk.h>
in the header directory, so just remove it.

Change-Id: I672335218abc8375610a368d84b1a005463a741a
Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/477223


Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Vitaliy Mysak <vitaliy.mysak@intel.com>