firmware/huc/bxt: Add huC Update for BXT

Add support for v1.8.2893 for BXT huC.
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>

WHENCE

@@ -3631,6 +3631,9 @@ Version: HuC API/ABI ver 1 - release 7 for Skylake
 File: i915/bxt_huc_ver01_07_1398.bin
 Version: HuC API/APB ver 1 - release 7 for Broxton
 
+File: i915/bxt_huc_ver01_8_2893.bin
+Version: HuC API/APB ver 1 - release 8 for Broxton
+
 File: i915/kbl_huc_ver02_00_1810.bin
 Version: HuC API/APB ver 2 - for Kabylake