[SCSI] ses: add support for enclosure component hot removal

Right at the moment, hot removal of a device within an enclosure does
nothing (because the intf_remove only copes with enclosure removal not
with component removal). Fix this by adding a function to remove the
component.  Also needed to fix the prototype of
enclosure_remove_device, since we know the device we've removed but
not the internal component number

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>