tcl/target: add BCM2835 configuration file

tcl/target: add BCM2835 configuration file

This is the Broadcom chip used in the Raspberry Pi Model A, B, B+,
the Compute Module, and the Raspberry Pi Zero.

Partial information is available in raspberry pi website:
https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2835

Change-Id: Ifeb012952473d624327e8c010ac5c886d9473aa0
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: http://openocd.zylin.com/6067
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>