slimbus: Fix struct and documentation alignment in stream.c

The placement of the `segdist_codes` array documentation was corrected
to conform with kernel documentation guidelines. The `@segdist_codes`
was placed incorrectly within the struct `segdist_code` documentation
block, which led to a potential misinterpretation of the code structure.

The `segdist_codes` array documentation was moved outside the struct
block, and a separate comment block was provided for it. This change
ensures that clarity and proper alignment with kernel documentation
standards are maintained.

A kernel-doc warning was addressed:
./drivers/slimbus/stream.c:49: warning: Excess struct member 'segdist_codes' description in 'segdist_code'

Signed-off-by: Amit Vadhavana <av2082000@gmail.com>
Reviewed-by: Ricardo B. Marliere <ricardo@marliere.net>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20240705080234.424587-2-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>