megaraid_sas: Fix instance access in megasas_reset_timer

megaraid_sas: Fix instance access in megasas_reset_timer

commit f575c5d3ebdca3b0482847d8fcba971767754a9e upstream.

The following patch for megaraid_sas will fix a potential bad pointer access
in megasas_reset_timer(), when a MegaRAID 9265/9285 or 9360/9380 gets a
timeout.  megasas_build_io_fusion() sets SCp.ptr to be a struct
megasas_cmd_fusion *, but then megasas_reset_timer() was casting SCp.ptr to be
a struct megasas_cmd *, then trying to access cmd->instance, which is invalid.

Just loading instance from scmd->device->host->hostdata in
megasas_reset_timer() fixes the issue.

Signed-off-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>