allow MCF532x to use CONFIG_MONITOR_IS_IN_RAM

CONFIG_MONITOR_IS_IN_RAM is broken for MCF532x. This patch fixes this
 by conditionally
- removing the vector table at the beginning of code
- not overwriting the vector base register
- removing the code to re-set the PLL, which effectively disables
  SDRAM access

Signed-off-by: Wolfgang Wegner <w.wegner@astro-kom.de>