sim3x: fix build failure with clang 3.6

sim3x: fix build failure with clang 3.6

This fixes a warning as reported by the current clang version:
../../../../src/flash/nor/sim3x.c:867:20: error: address of array
'sim3x_info->device_package' will always evaluate to 'true' .

Change-Id: Ie160cbe6df8f491e9beff38d47e2f13575529bf9
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-on: http://openocd.zylin.com/2838
Tested-by: jenkins
Reviewed-by: Oleksij Rempel
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>