Platforms with Disabled devices cause app crash for OCL apps.

[manocharahul]

1. currently clinfo detects all platforms even if the underlying device is disabled.
2. This is fine for clinfo, but the OCL apps (Geekbench/Luxmark) crash when they see CL_DEVICE_NOT_FOUND returned by OCL.
3. ProbeDevice() (icd_windows_hkr.c) only screens for reboot-pending states, so a device that has been disabled in Device Manager is still reported as Valid. Disabling a device does not remove its registry values, so the loader goes on to read OpenCLDriverName from the disabled adapter's HKR software key and registers an ICD for hardware that can never supply an OpenCL device.
4. The fix is to check if the device has been disabled with CM_PROB_DISABLED and skip enumerating its ICD via HKR.

I have tested the fix but unable upstream the change, due to write permissions.

[manocharahul]

#288

[manocharahul]

Can someone review my PR #288 . It still shows CLA not signed, even though i have signed it multiple times.