arm64: bcm2835: Drop select of nonexistent HAVE_ARM_ARCH_TIMER

Unlike on arm32, the HAVE_ARM_ARCH_TIMER config symbol does not exist on
arm64.

Note that the toplevel ARM64 symbol always selects ARM_ARCH_TIMER, so
support for it is always included.

Fixes: 628d30d1 ("arm64: Add platform selection for BCM2835.")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>