powerpc/configs: Drop unnecessary CONFIG_POWERNV_OP_PANEL

In commit 43a1dd9b ("powerpc/powernv: Add driver for operator
panel on FSP machines") we added CONFIG_POWERNV_OP_PANEL=m to the
powernv defconfig, but it's default m so that's no necessary.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/powernv_defconfig

@@ -187,7 +187,6 @@ CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_JSM=m
 CONFIG_VIRTIO_CONSOLE=m
-CONFIG_POWERNV_OP_PANEL=m
 CONFIG_IPMI_HANDLER=y
 CONFIG_IPMI_DEVICE_INTERFACE=y
 CONFIG_IPMI_POWERNV=y