ar71xx: qihoo-c301: reset imageNtrynum after each successful boot.

ar71xx: qihoo-c301: reset imageNtrynum after each successful boot.

Qihoo C301 has 2 flash chips of which one is used as primary and the
other is used as backup.  OEM U-Boot will try to boot an activeregion N
with imageNstatus=0 and imageNtrynum <= imagemaxtry.  If such a region
is found, bootloader will try to increment imageNtrynum and boot it.

This patch tries to reset imageNtrynum after each successful boot (if
the boot process reaches the execution of /etc/init.d/done).

	root@OpenWrt:/# hexdump -C -n 128 /dev/mtdblock9
	00000000  9e f3 63 91 61 63 74 69  76 65 72 65 67 69 6f 6e  |..c.activeregion|
	00000010  3d 31 00 69 6d 61 67 65  31 73 74 61 74 75 73 3d  |=1.image1status=|
	00000020  30 00 69 6d 61 67 65 32  73 74 61 74 75 73 3d 30  |0.image2status=0|
	00000030  00 69 6d 61 67 65 32 74  72 79 6e 75 6d 3d 30 00  |.image2trynum=0.|
	00000040  69 6d 61 67 65 6d 61 78  74 72 79 3d 33 00 69 6d  |imagemaxtry=3.im|
	00000050  61 67 65 31 74 72 79 6e  75 6d 3d 30 00 00 00 00  |age1trynum=0....|
	00000060  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
SVN-Revision: 42914