smem_unit stays inside the core, and the two separate buses to dcache
and smem are exposed at VX_core.
Currently core_wrapper ties req valid to 1'b0, stalling kernels that
reads from sharedmem.
Since the core's response ready signal depends on response valid, but core does
not accept write ACKs, we need to manually assert ready when there is a valid
response coming in for a write regardless of the core's ready state (which would
be 0).
Need to use DCACHE_NOSM_TAG_WIDTH instead of DCACHE_TAG_WIDTH; otherwise, the
`ASSIGN_VX_MEM_BUS_IF macro in VX_smem_unit.sv does assignment of packed structs
with different widths for the tag field, resulting in misaligned bit error.
This results in wrong memory addresses for the core requests.
Richard Yan