All ARMV7-M IRQ setup: Always set the NVIC vector table address. This is...

All ARMV7-M IRQ setup:  Always set the NVIC vector table address.  This is needed in cases where the code is running with a bootload and when the code is running from RAM.  It is also needed by the logic of up_ramvec_initialize() which gets the vector base address from the NVIC.  Suggested by Pavel Pisa