axi_ad7606x: Fix DRP locked

software expects DRP locked to be 1 and it should be set to 1 if not
used

https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git/commit/?h=testing&id=70a0e10f8ab62ba82b080347ca0a119e14e964c9
(cherry picked from commit 7d0a4ce)

Author: sarpadi

library/axi_ad7606x/axi_ad7606x.v

@@ -419,7 +419,7 @@ module axi_ad7606x #(
     .up_drp_wdata (),
     .up_drp_rdata (),
     .up_drp_ready (),
-    .up_drp_locked (),
+    .up_drp_locked (1'b1),
     .adc_config_wr (wr_data_s),
     .adc_config_ctrl (adc_config_ctrl_s),
     .adc_config_rd ({16'd0, rd_data_s}),