bindings: input: qcom-hv-haptics: Change to use 8-bit FIFO data

Hardware with revision 2 is changed to use 8-bit FIFO memory while
revision 1 is using 9-bit FIFO memory. To unify the data assignment
from devicetree, change to use 8-bit data for "qcom,wf-fifo-data"
property. Software can expand the 8-bit data to 9-bit for V1
hardware accordingly.

Change-Id: I00749a3cb395bf38ffd4d0cc9fd48de29b949c6d