MdePkg/HiiImageDecoder.h: Rename from ImageDecoder.h

Rename the protocol header file to follow EDKII file
name rule before the HiiImageDecoder protocol is used
by anyone.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
diff --git a/MdePkg/Include/Protocol/ImageDecoder.h b/MdePkg/Include/Protocol/HiiImageDecoder.h
similarity index 100%
rename from MdePkg/Include/Protocol/ImageDecoder.h
rename to MdePkg/Include/Protocol/HiiImageDecoder.h