* [Bugfix] [VTA] VTA DRAM Have A Logic Issue May Cause GEMM Output Wrong.

Symptom:
after change “LOG_BLOCK_IN” and “LOG_BLOCK_OUT” from vta_config.json
into 7, run vta "Simple Matrix Multiply" in "simulator", the vta
calculate result for GEMM is wrong.

Sometime VTA crash with error “Check failed: phy_addr != 0 (0 vs. 0) :
trying to get address that is nullptr”

Analysis:
Simulator hardcode kPageSize into 1<<12 and physical address calculate
based on this size, when doing “insn->dram_base” calculation , because
GetElemBytes(dst_memory_type) larger than page size, different physcial
address may get same dram_base, than caused logic issue and finally
trigger GEMM out put is wrong.

Solution:
add logic to check if PAGE SIZE larger then "GetElemBytes" return value.

* address review comments.