sensors: lsm6dsv16x: fix get_frame_count API #150483

Job	Run time
twister-build-prep / prep_pr	2m 56s
twister-build-prep / prep_push	0s
twister-build (1)	25m 10s
twister-build (2)	27m 38s
twister-build (3)	25m 39s
twister-build (4)	31m 47s
twister-build (5)	23m 26s
twister-build (6)	21m 42s
twister-build (7)	30m 19s
Publish Unit Tests Results	13s
Check Twister Status / all jobs passed	1s
	3h 8m 51s

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