skia: Fix a bug in clampx_nofilter_trans_S16_D32_DX

When scaling a line, in the case of the last pixel needing to be
duplicated, the beginning of the line is getting clobbered with wrong
value.  This is because dest buffer pointer is not moved forward.  Fix
that by adding pointer update line.

CRs-Fixed: 349571

Change-Id: Id6dc41d7e6bd2b777097f62e788bd2476609a9ae