Modify sample buffer size for larger displays.

Modifies the intermediate buffer size for sample pixel indexes, used in the
sample proc function calls. If the buffer is not large enough, the job is split
into several calls. This would impact the performance of SIMD optimizations.

Change-Id: I86848d1c44fe338258b40f6ee6a576289cebd496
Signed-off-by: Henrik Smiding <henrik.smiding@stericsson.com>
Signed-off-by: Patrik Ryd <patrik.ryd@stericsson.com>