Update golobal to Shared Memory operation

[LoserCheems]

This pull request refactors the handling of the causal mask in the compute_attn_1rowblock function to improve code clarity and maintainability. Instead of using a ternary operator to conditionally initialize tCausalMaskgCausalMask and tCausalMasksCausalMask, the code now uses a more explicit if block.

Key change in causal mask handling:

• csrc/src/flash_attention_fwd_kernel.h: Replaced the ternary operator with an if block for initializing tCausalMaskgCausalMask and tCausalMasksCausalMask when has_causal_mask is true. This refactor improves readability and ensures that the variables are only initialized when necessary.