arm: dsputil: fix overreads in put/avg_pixels functions

The vertically interpolating variants of these functions read
ahead one line to optimise the loop.  On the last line processed,
this might be outside the buffer.  Fix these invalid reads by
processing the last line outside the loop.

Signed-off-by: Mans Rullgard <mans@mansr.com>
arm: dsputil: prettify some conditional instructions in put_pixels macros

Signed-off-by: Mans Rullgard <mans@mansr.com>
arm/neon: dsputil: use correct size specifiers on vld1/vst1

Change the size specifiers to match the actual element sizes
of the data.  This makes no practical difference with strict
alignment checking disabled (the default) other than somewhat
documenting the code.  With strict alignment checking on, it
avoids trapping the unaligned loads.

Signed-off-by: Mans Rullgard <mans@mansr.com>