target & board: AT91SAM7A2 and Olimex SAM7-LA2

Initial Support for AT91SAM7A2 on Olimex SAM7-LA2 board.
The board seems not to be able to reset into halted mode, as srst is
connected to NRESET of the cpu (configured srst_pulls_trst).
JTAG RCLK is connected to CLK.
Tested with interface/ftdi/olimex-arm-usb-ocd-h.cfg.

Change-Id: I2bdd67e3683e45f1119c5850bad294aa107891d8
Signed-off-by: Arne Wichmann <arne.wichmann@gmail.com>
Reviewed-on: http://openocd.zylin.com/2318
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

tcl/target/at91sam7a2.cfg

@@ -0,0 +1,23 @@
+
+if { [info exists CHIPNAME] } {
+   set _CHIPNAME $CHIPNAME
+} else {
+   set _CHIPNAME at91sam7a2
+}
+
+if { [info exists ENDIAN] } {
+   set _ENDIAN $ENDIAN
+} else {
+   set _ENDIAN little
+}
+
+if { [info exists CPUTAPID] } {
+   set _CPUTAPID $CPUTAPID
+} else {
+   set _CPUTAPID 0x1f0f0f0f
+}
+
+jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_CPUTAPID
+set _TARGETNAME $_CHIPNAME.cpu
+
+target create $_TARGETNAME arm7tdmi -endian $_ENDIAN -chain-position $_TARGETNAME