After the removable of get_vmalloc_info(), the unused global memory
variables, and the optional dcache/icache shrinkers there is no
longer a need for the kallsyms compatibility code. This allows
us to eliminate another brittle area of the code by removing the
kernel upcall this functionality depended on for older kernels.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>