tsc210x: fix buffer overrun on invalid state load

tsc210x: fix buffer overrun on invalid state load

CVE-2013-4539

s->precision, nextprecision, function and nextfunction
come from wire and are used
as idx into resolution[] in TSC_CUT_RESOLUTION.

Validate after load to avoid buffer overrun.

Cc: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 5193be3be35f29a35bc465036cd64ad60d43385f)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>