[COMMON] media: mfc: fix the QoS calculation

[COMMON] media: mfc: fix the QoS calculation

If too many instances are open,
'total_fps * sw_time' can exceed 1 second and total_mb value can be zero.
When the total_mb is zero,
we can't request a high QoS level in qos_on function
and QoS remove will be called unconditionally in qos_off function.
In order to defend this problem,
It has been modified to use max_mb value if SW time exceeds 1 second.

Change-Id: I833bc27b5c547c8d92c5eddc9f685d26677b179f
Signed-off-by: Jeonghee Kim <jhhhh.kim@samsung.com>