accel/amdxdna: Refactor GEM BO handling and add helper APIs for address retrieval

accel/amdxdna: Refactor GEM BO handling and add helper APIs for address retrieval

Refactor amdxdna GEM buffer object (BO) handling to simplify address
management and unify BO type semantics.

Introduce helper APIs to retrieve commonly used BO addresses:
- User virtual address (UVA)
- Kernel virtual address (KVA)
- Device address (IOVA/PA)

These helpers centralize address lookup logic and avoid duplicating
BO-specific handling across submission and execution paths. This also
improves readability and reduces the risk of inconsistent address
handling in future changes.

As part of the refactor:
- Rename SHMEM BO type to SHARE to better reflect its usage.
- Merge CMD BO handling into SHARE, removing special-case logic for
  command buffers.
- Consolidate BO type handling paths to reduce code duplication and
  simplify maintenance.

No functional change is intended. The refactor prepares the driver for
future enhancements by providing a cleaner abstraction for BO address
management.

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Max Zhen <max.zhen@amd.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260320210615.1973016-1-lizhi.hou@amd.com