[mlir] Linalg tiling: generate code avoding out-of-bounds accesses
After the subview operation was migrated from Linalg to Standard, it changed
semantics and does not guarantee the absence of out-of-bounds accesses through
the created view anymore. Compute the size of the subview to make sure it
always fits within the view (subviews in last iterations of the loops may be
smaller than those in other iterations).
Differential Revision: https://reviews.llvm.org/D73614