Add initial memorymap for Vybrid VF6xx module. Also add the clock
control module which allows to control system clocks and enable
clocks of individual pheripherials.
Freescale Vybrid is a familiy of ARM SoC, wheras the VF6xx models
have two cores in one SoC, a Cortex-A5 and a Cortex-M4. This adds
initial support for the Cortex-M4 in the libopencm3 library.
By using two different ram areas (pc_ram and ps_ram) the user can
put the code in a RAM area bounded to the code bus. The data can
be stored in the data area. However, currently the initial values
of for the variables in the data section are stored in the code
section and copied to the ram section by the initialization code
(like it's copied from ROM to RAM on microcontrollers).
