[bug] Stuck when msg_len is 128

[yintianyu]

I'm using @a94dcf3, which is the current version of Chipyard.
I set the parameters as default, where Sha3FastMem is true.B and Sha3WidthP is 64 thus round_size_words is 17.
When msg_len is 128, Controller's mem_s will stick at m_read, and cannot tranfer to mem_pad because when mindex becomes 0x10, it happens to be not smaller than round_size_words - 1 but smaller than round_size_words, then it sticks at Line 293.