[NFC][Linalg] Remove redundant doc comments from Conv matchers (#172344)
-- This commit removes the redundant doc comments pertaining
to indexing maps of convolution ops from their respective matchers.
-- This is being done because the code self-documents the same and is
a follow-up based on
https://github.com/llvm/llvm-project/pull/172141#discussion_r2619129513
Signed-off-by: Abhishek Varma <abhvarma@amd.com>