input: sensors: add null terminator in dt match table

A previous change removed the null termimator on apds993X_match_table.
This may cause a potential crash. Add it back to fix the issue.

CRs-fixed: 678338
Change-Id: If091b89f2031fc4a35f954639ad799103026abd9
Signed-off-by: Oliver Wang <mengmeng@codeaurora.org>