arm64: dts: ls1012a: enable PCIe on freeway board

ls1012a-freeway board contains a M.2 2230 slot. Update the status of
pcei1 node to okay so that the pcie controller can be probed.

Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>