[nrf fromtree] Revert "boards: nordic: nRF54L15DK: set HFXO clock latency to 854"

This reverts commit d0a0769.

The reason for reverting this is that the only safe startup time for
54L series is the one defined in the SoC .dtsi files (1650us), and other
startup times are not reliable even when tested on a particular board.

Signed-off-by: Carles Cufi <[email protected]>
(cherry picked from commit 9e52df0)

Author: carlescufi

boards/nordic/nrf54l15dk/nrf54l15dk_common.dtsi

@@ -108,9 +108,5 @@
 	pinctrl-names = "default", "sleep";
 };
 
-&hfxo {
-	startup-time-us = <854>;
-};
-
 /* Get a node label for wi-fi spi to use in shield files */
 wifi_spi: &spi22 {};