mtd: add linksys_bootcount for ramips

Reset bc is needed for Linksys EA7500 v2's dual boot.

Size impact (tested with Linksys EA7500 v2 @ mt7621):

mtd_25_mipsel_24kc.ipk: 13174 -> 13628 (454 bytes)
initramfs: 3660350 -> 3660688 (338 bytes)

Signed-off-by: Davide Fioravanti <pantanastyle@gmail.com>
[add size impact information]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

package/system/mtd/src/Makefile

@@ -14,7 +14,7 @@ obj.brcm = trx.o
 obj.bcm47xx = $(obj.brcm)
 obj.bcm53xx = $(obj.brcm) $(obj.seama)
 obj.bcm63xx = imagetag.o
-obj.ramips = $(obj.seama) $(obj.tpl) $(obj.wrg)
+obj.ramips = $(obj.seama) $(obj.tpl) $(obj.wrg) linksys_bootcount.o
 obj.mvebu = linksys_bootcount.o
 obj.kirkwood = linksys_bootcount.o
 obj.ipq806x = linksys_bootcount.o