staging: unisys: uislib: uislib.c: sparse warning of context imbalance

fixed sparse warning : context imbalance in 'destroy_device'
                        unexpected unlock
this patch will generate warning from checkpatch for
lines over 80 character , but since those are user-visible strings
so it was not modified.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Tested-by: Benjamin Romer <benjamin.romer@unisys.com>
Acked-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>