dtc: Remove unused check variable

Commit 376ab6f2 removed the old style check functionality from DTC,
however the check option and variable were not removed.  This leads to
build failures when -Werror=unused-but-set-variable is specified:

	dtc.c: In function 'main':
	dtc.c:102:17: error: variable 'check' set but not used [-Werror=unused-but-set-variable]
	cc1: all warnings being treated as errors
	make: *** [dtc.o] Error 1
	make: *** Waiting for unfinished jobs....

Remove the check variable.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
1 file changed