x86: hevc_mc: load less data in epel filters

Before:
5679 decicycles in epel_bi, 2059976 runs, 37176 skips
3468 decicycles in epel_uni, 1040886 runs, 7690 skips

After:
5323 decicycles in epel_bi, 2059493 runs, 37659 skips
3262 decicycles in epel_uni, 1040871 runs, 7705 skips

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>