DynamicTablesPkg: Rename SBSA generic watchdog

DynamicTablesPkg: Rename SBSA generic watchdog

Buzilla: 3565 (https://bugzilla.tianocore.org/show_bug.cgi?id=3565)

As part of the updates to ACPI 6.4 the "SBSA Generic Watchdog" was
renamed to the "Arm Generic Watchdog". This patch implements that
change by updating the GTDT generator to use Acpi64.h and renames
any occurence of "SBSA Generic Watchdog" to "Arm Generic Watchdog".

Signed-off-by: Chris Jones <christopher.jones@arm.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>