tcl: Add default hooks for STM32F4x

Set up PLL and increase clock at reset init.

Change-Id: I611bc6fb7c0c5afd8ed3f4ad8e64f3c7b981d31c
Signed-off-by: Uwe Bonnes <bon@elektron.ikp.physik.tu-darmstadt.de>
Reviewed-on: http://openocd.zylin.com/2609


Tested-by: jenkins
Reviewed-by: Rémi PRUD'HOMME <prudhomme.remi@gmail.com>
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>