spmi_controller_alloc() currently returns NULL to all types of errors,
which can be improved.

Use appropriate error code in returns and pass the errors from used
functions where possible.
Signed-off-by: Fei Shao <fshao@chromium.org>
Link: https://lore.kernel.org/r/20230824104101.4083400-6-fshao@chromium.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20231206231733.4031901-8-sboyd@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>