i915: Add DMC firmware v2.06 for TGL

Minor fixes around context restore.
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>

WHENCE

@@ -4028,6 +4028,9 @@ Version: Huc API/APB ver 8 release 4 for Icelake
 File: i915/tgl_dmc_ver2_04.bin
 Version: DMC API/APB ver 2 release 4 for Tigerlake
 
+File: i915/tgl_dmc_ver2_06.bin
+Version: DMC API/APB ver 2 release 6 for Tigerlake
+
 File: i915/icl_huc_9.0.0.bin
 Version: Huc API/APB ver 9 release 0 for Icelake