Fix off-by-one error in XMF node limit checking

The treeEnd field in XMF is inclusive, while the endOffset convention
we're using is exclusive. This caused some valid files to be rejected,
for example external/sonivox/arm-wt-22k/vectors/Leadsol.mxm).

Test: Tested the file above from command line.
Bug: 126380818
Change-Id: I61a950d592e8a20a43d8cd7810ab78317df3af1d