Update hdf5_data_layer.cpp

Fixing a bug.

The bug is in the following lines:

top[0]->Reshape(batch_size, data_blob_.channels(),
data_blob_.width(), data_blob_.height());
top[1]->Reshape(batch_size, label_blob_.channels(),
label_blob_.width(), label_blob_.height());

It should be:

top[0]->Reshape(batch_size, data_blob_.channels(),
data_blob_.height(), data_blob_.width());
top[1]->Reshape(batch_size, label_blob_.channels(),
label_blob_.height(), label_blob_.width());

The implication of the bug, is that when images that are loaded by the hdf5_data_layer with height != width, the original images will get scrambled.