msm: camera: isp: Fix the framedrop pattern for burst streams

Framedrop pattern has 1 for num_burst_capture followed by 0 for
init_frame_drop. Previously we were using wrong variable
num_frame_count which had value 2 instead of 1 which caused
IOMMU faults.

Change-Id: I347df840253fca64db715dfbc90ce1065fe87a5b
Signed-off-by: Harsh Shah <harshs@codeaurora.org>