some files rename

diff --git a/modules/gpu/src/cuda/beliefpropagation.cu b/modules/gpu/src/cuda/stereobp.cu
similarity index 100%
rename from modules/gpu/src/cuda/beliefpropagation.cu
rename to modules/gpu/src/cuda/stereobp.cu

diff --git a/modules/gpu/src/beliefpropagation.cpp b/modules/gpu/src/stereobp.cpp
similarity index 100%
rename from modules/gpu/src/beliefpropagation.cpp
rename to modules/gpu/src/stereobp.cpp