fm3: fix Fujitsu MB9Ax family support

fm3: fix Fujitsu MB9Ax family support

Some MB9Ax (especially few internal SRAM model) fails programming
because of wrong SRAM basic-address on running algorithm.
Default SRAM basic-address must be 0x20000000.
This patch is fixing default SRAM basic-address and ramcode offset.
Tested on a MB9BF618T and MB9AF112K.

Change-Id: Ibda9aceb4c317bcae0dcce9f6d0fd1c4b5d81952
Signed-off-by: Nemui Trinomius <nemuisan_kawausogasuki@live.jp>
Reviewed-on: http://openocd.zylin.com/1793
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>