libswscale/ppc/swscale_altivec.c : fix hScale_altivec_real()...

libswscale/ppc/swscale_altivec.c : fix hScale_altivec_real() yuv2planeX_16_altivec() yuv2planeX_8() for little endian

add marcos GET_LS() GET_VF() LOAD_FILTER() LOAD_L1() GET_VF4() FIRST_LOAD() UPDATE_PTR() LOAD_SRCV() LOAD_SRCV8() GET_VFD() for POWER LE
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>