### What this PR does / why we need it?
dispatch_ffn_combine use hccl buffer as shared buffer, if hccl buffer
not enough，operator will error with "MTE out of range"
now add check for hccl buffer size, if not enough, will prompt "hccl
buffer is too small" and indicate what the expectation is.
### Does this PR introduce _any_ user-facing change?
N/A
### How was this patch tested?
- vLLM version: v0.13.0
- vLLM main:
d68209402d
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Signed-off-by: lhchg <lhao_cheng@163.com>
27a513b672