raiden_debug_spi: Use new API to register shutdown function

This allows programmer to register shutdown function in spi_master
struct, which means there is no need to call register_shutdown in init
function, since this call is now a part of register_spi_master.

As a consequence of using new API, two things are happening here:
1) No resource leakage anymore in case register_shutdown() would fail,
2) Fixed propagation of register_spi_master() return values.

BUG=b:185191942
TEST=test in CB:57918
(Nikolai) tested probe/read/write with a servo micro and puff board

Change-Id: I8927224779f24d1fda088991337e54d7272775a6
Signed-off-by: Anastasia Klimchuk <aklm@chromium.org>
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M raiden_debug_spi.c
1 file changed, 2 insertions(+), 4 deletions(-)