fixed gpr_ram bug + io bus arbitration

hw/opae/sources.txt

@@ -99,7 +99,7 @@ vortex_afu.json
 ../rtl/VX_inst_multiplex.v
 ../rtl/VX_lsu_addr_gen.v
 ../rtl/VX_dcache_io_arb.v
-../rtl/VX_dram_arb.v
+../rtl/VX_mem_arb.v
 
 ../rtl/pipe_regs/VX_f_d_reg.v
 ../rtl/pipe_regs/VX_i_d_reg.v