Revert "Apply md_additional_offset before multiplying in rel gain step"

This reverts commit b6111074.

src/calng/kernels/agipd_gpu.cu

@@ -120,10 +120,10 @@ extern "C" {
 				}
 				// TODO: baseline shift
 				if (corr_flags & REL_GAIN_PC) {
+					corrected *= rel_gain_pc_map[gm_map_index];
 					if (gain == 1) {
 						corrected += md_additional_offset[map_index];
 					}
-					corrected *= rel_gain_pc_map[gm_map_index];
 				}
 				if (corr_flags & GAIN_XRAY) {
 					corrected = (corrected / rel_gain_xray_map[map_index]) * g_gain_value;