soc: qcom: socinfo: correct the name of softsku_id

Correct the softsku_id name to softsku_idx So, that post
boot scripts get this values.

Change-Id: Id7674a0557a99586b6b26f3cb3eab2819c90d272
Signed-off-by: Chetan C R <quic_cchinnad@quicinc.com>