rockchip: puma-rk3399: remove duplicate code (merge artifact)

A few lines (defines and declarations) had been duplicated when the
puma-rk3399 board was initially merged.  This removes the duplicates
and changes the style to use local constants instead of pasted
literals.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
[fixed up commit-message & converted to use 'const u32':]
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>