To make software license auditing simpler, use SPDX[0] license
identifiers instead of duplicating the license text in every file.

NOTE: Files that have been imported by FreeBSD have not been modified.

[0]: https://spdx.org/

Change-Id: I80a00e1f641b8cc075ca5a95b10607ed9ed8761a
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

Based on SP805 Programmer's model (ARM DDI 0270B). This driver
provides three public APIs:

    void sp805_start(uintptr_t base, unsigned long ticks);
    void sp805_stop(uintptr_t base);
    void sp805_refresh(uintptr_t base, unsigned long ticks);

Upon start, the watchdog starts counting down from the number of
ticks specified. When the count reaches 0 an interrupt is triggered.
The watchdog restarts counting down from the number of ticks
specified. If the count reaches 0 again, the system is reset. A
mechanism to handle the interrupt has not been implemented. Instead,
the API to refresh the watchdog should be used instead to prevent a
system reset.

Change-Id: I799d53f8d1213b10b341a4a67fde6486e89a3dab