[pooling] Do not allocate memory in initialize

[pooling] Do not allocate memory in initialize

Set batch size in initialize for pooling layer allocates memory.
However, the final batch size is allowed to change in inference/training.
This unnecessarily changes the peak memory requirement.
For now, this memory is allocated with forwarding.
Later this will be handled as a tensor with manager once int data type is supported.

**Self evaluation:**
1. Build test: [x]Passed [ ]Failed [ ]Skipped
2. Run test: [x]Passed [ ]Failed [ ]Skipped

Signed-off-by: Parichay Kapoor <pk.kapoor@samsung.com>