staging: mt7621-pci: remove conditional compilation.

Code currently defines:

#define CONFIG_PCIE_PORT0
#define CONFIG_PCIE_PORT1
#define CONFIG_PCIE_PORT2
#define GPIO_PERST

and then compiles code only if they are defined.
We might want to disable some of these via devicetree one
day, but for now just remove the #defines and the
conditions - all the code for different ports is
easy to identify.

Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>