interconnect: qcom: sm6115: Unspaghettify SNoC QoS port numbering

When I was creating this driver, my bright mind overlooked the existence
of desc->qos_offset and decided to make up for the difference it made by
adding 21 (0x15) to the port index on SNoC and its downstream buses.

Undo this mistake to make the indices actually mean something.

Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240326-topic-rpm_icc_qos_cleanup-v1-1-357e736792be@linaro.org
Signed-off-by: Georgi Djakov <djakov@kernel.org>