Fix the bug that pmon can't update itself if its size larger than 512k

If size of "gzrom.bin" is above 512K, during running "load -r -f 0xbfc00000 ..."
commands, the error below will occures
"Loading file: tftp://10.2.5.27/gz.bin (bin) |
Loaded 536604 bytes
Programming flash 83000000:8301c into bfc00000
Erase failed!"

Now we do below works:
1. Modify address of enviroment
2. Modify the max size of bios to 1M
Thanks <wangxiyue@loongson.cn>

Target:Bonito3aserver

Targets/Bonito3a780e/include/bonito.h

@@ -58,7 +58,7 @@ extern char           *heaptop;
 #ifdef NVRAM_IN_FLASH
 #	define	NVRAM_SIZE		494
 #	define	NVRAM_SECSIZE		500
-#	define	NVRAM_OFFS		0x0007f000
+#	define	NVRAM_OFFS		0x000ff000
 #	define ETHER_OFFS		494 	/* Ethernet address base */
 #else	/* Use clock ram, 256 bytes only */
 #	define NVRAM_SIZE		114

Targets/Bonito3aserver/dev/pflash_tgt.h

@@ -48,7 +48,7 @@
  */
 
 #define	TARGET_FLASH_DEVICES_16 \
-    { PHYS_TO_UNCACHED(BONITO_FLASH_BASE), 0x00080000, 1, 1, FL_BUS_8  },	\
+    { PHYS_TO_UNCACHED(BONITO_FLASH_BASE), 0x00100000, 1, 1, FL_BUS_8  },	\
     { PHYS_TO_UNCACHED(0x1e000000), 0x02000000, 1, 1, FL_BUS_16  },	\
     { 0x00000000, 0x00000000 }
 

Targets/Bonito3aserver/include/bonito.h

@@ -58,7 +58,7 @@ extern char           *heaptop;
 #ifdef NVRAM_IN_FLASH
 #	define	NVRAM_SIZE		494
 #	define	NVRAM_SECSIZE		500
-#	define	NVRAM_OFFS		0x0007f000
+#	define	NVRAM_OFFS		0x000fd800
 #	define ETHER_OFFS		494 	/* Ethernet address base */
 #else	/* Use clock ram, 256 bytes only */
 #	define NVRAM_SIZE		114