CHART PREVIEW: LET'S DO THE NUMBERS   Katy Perry's Witness (Capitol) lands at #1 on our SPS chart this week with 187k.    Two other debuts, from Capitol Nashville's Lady Antebellum and TDE/RCA's SZA, also earn spots in the Top 5 with 60k and 55k, respectively. Top Dawg Entertainment has two titles near the top, it should be noted, as TDE/Interscope's Kendrick Lamar remains at #2 with 71k.   Virgin