[CK] Small improvements for grouped conv backward weight
(#4872)
## Motivation
Improvements for CK Tile convolution builder run function and atol/rtol
calculations.
## Technical Details
- Add preprocessing function for wrw when k_batch is larger than 1 for
builder run function
- Divide num acums by number of groups to get real number of accums
## Test Plan
CI wrw tests
## Test Result
pending
## Submission Checklist
- [x] Look over the contributing guidelines at
https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.
AICK-783
eede24de0d