arm64: dts: stratix10: add status to qspi dts node

Add status = "okay" to QSPI node.

Fixes: 0cb140d0 ("arm64: dts: stratix10: Add QSPI support for Stratix10")
Cc: linux-stable <stable@vger.kernel.org> # >= v5.6
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>