sunxi: Make CONFIG_DRAM_TPR3 apply to sun[57]i

The tpr3 (timing skew) parameter is used in all supported versions of
the sunxi DRAM controller, but it was only enabled for sun4i in
47e3501a.

Signed-off-by: Adam Sampson <ats@offog.org>
Acked-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>