RDMA/ionic: Add Makefile/Kconfig to kernel build environment

Add ionic to the kernel build environment.

Co-developed-by: Allen Hubbe <allen.hubbe@amd.com>
Signed-off-by: Allen Hubbe <allen.hubbe@amd.com>
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Link: https://patch.msgid.link/20250903061606.4139957-15-abhijit.gangurde@amd.com


Signed-off-by: Leon Romanovsky <leon@kernel.org>