aspeed/i2c: Fix DMA address mask

The RAM memory region is now used for DMAs accesses instead of the
memory address space region. Mask off the top bits of the DMA address
to reflect this change.

Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20210407171637.777743-4-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

hw/i2c/aspeed_i2c.c

@@ -601,7 +601,7 @@ static void aspeed_i2c_bus_write(void *opaque, hwaddr offset,
             break;
         }
 
-        bus->dma_addr = value & 0xfffffffc;
+        bus->dma_addr = value & 0x3ffffffc;
         break;
 
     case I2CD_DMA_LEN: