ARM: 8822/1: smp_twd: Remove legacy TWD registration

As of commit 7484c727

 ("ARM: realview: delete the RealView board
files"), the ARM Timer and Watchdog Unit is instantiated from DT only.
Moreover, the driver is selected from ARCH_MULTIPLATFORM platforms only,
which implies OF, TIMER_OF, and COMMON_CLK.

Hence remove all unused legacy infrastructure from the driver.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>