riscv: dts: microchip: remove unused pcie clocks

The PCIe root port in the designs that ship with the PolarBerry and
M100PFSEVP are connected via one, not two Fabric Interface Controllers
(FIC). The one at 0x20_0000_0000 is fic0, so remove the fic1 clocks from
the dt node.

The same clock provides both, so this is harmless but inaccurate.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>