platform: generic: allwinner: sun20i-d1: Remove duplicated CSR definitions

All T-Head CSRs are already defined in thead/c9xx_encoding.h.
Let's reuse the values from there instead of redefining them with
a slightly different name.

Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Reviewed-by: Anup Patel <anup@brainfault.org>