soc: qcom: dfc: Fix qmi indication size

Fix decoded size of an indication message to be the size after
decoding. Incorrect size could lead to invalid memory access.

CRs-fixed: 2446770
Change-Id: I5e982fbb879a28419081990a773920fb536763b3
Acked-by: Weiyi Chen <weiyic@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>