REFAC: use macro to manage static loop of ChnlGrid and IntegGrid

[Dengda98]

#define GRT_LOOP_ChnlGrid(im, c) \
    for(int im = 0; im < GRT_SRC_M_NUM; ++im) \
        for(int c = 0; c < GRT_CHANNEL_NUM; ++c)

#define GRT_LOOP_IntegGrid(im, v) \
    for(int im = 0; im < GRT_SRC_M_NUM; ++im) \
        for(int v = 0; v < GRT_INTEG_NUM; ++v)