When a device have bootloader on flash, user can set a offset that may
try erase and/or override the bootloader.  Add an exception to abort on
any of that conditions.

Signed-off-by: Gerson Fernando Budke <[email protected]>

The SAM4L SoC have a special flash controller on the whole family.  Add
CalwFlash controller to allow bossac work with SAM4L SoC family.

Signed-off-by: Gerson Fernando Budke <[email protected]>

This enables SAM4L SoC family support on BOSSA.

Note: SAM4L SoC family doesn't have SAM-BA boot rom. User needs
compile and set all configuration to allow use any SAM-BA host
like BOSSA.

Signed-off-by: Gerson Fernando Budke <[email protected]>

The SAM4L doesn't have an user interface to access the reset
controller.  Add Cortex-M4 NVIC reset instructions to allow
use of parameter -R.

Signed-off-by: Gerson Fernando Budke <[email protected]>