arm: mvebu: Avoid reading MVEBU_REG_PCIE_DEVID register too many times

arm: mvebu: Avoid reading MVEBU_REG_PCIE_DEVID register too many times

Change detection of platform/cpu from runtime to compile time via config
define. This completely eliminates compiling code which is not going to run
on selected platform. Code which parses and prints device / revision id
still reads device id from MVEBU_REG_PCIE_DEVID register, but only once.

Signed-off-by: Pali Rohár <[email protected]>
Acked-by: Marek Behún <[email protected]>
Reviewed-by: Stefan Roese <[email protected]>