[SCSI] ibmvscsi kexec fix

This makes ibmvscsi work correctly with the recent set of kexec
patches that went in.  This is based on work by Michael Ellerman, who
chased this initially.  He validated that it works during kexec.

Handle kexec correctly in ibmvscsi.   During kexec the adapter
will not get cleaned up correctly, so we may need to reset it
to make it sane again.

Signed-off-by: Dave Boutcher <sleddog@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>