applications: nrf_desktop: Disable Bluetooth LE Security mode 2 support

Change disables the deprecated `CONFIG_BT_SIGNING` Kconfig option. The
application relies on Bluetooth LE security mode 1 and security level of
at least 2 to ensure data confidentiality through encryption.

Jira: NCSDK-36689

Signed-off-by: Marek Pieta <[email protected]>

Author: MarekPieta

applications/nrf_desktop/Kconfig.ble

@@ -13,7 +13,6 @@ config DESKTOP_BT
 	imply DESKTOP_BLE_BOND_ENABLE
 	select BT
 	select BT_SETTINGS
-	select BT_SIGNING
 	select BT_SMP
 	imply BT_CONN_TX_NOTIFY_WQ if BT_LL_SOFTDEVICE
 	help

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -203,7 +203,8 @@ nRF5340 Audio
 nRF Desktop
 -----------
 
-|no_changes_yet_note|
+* Updated the :option:`CONFIG_DESKTOP_BT` Kconfig option to no longer select the deprecated :kconfig:option:`CONFIG_BT_SIGNING` Kconfig option.
+  Application relies on Bluetooth LE security mode 1 and security level of at least 2 to ensure data confidentiality through encryption.
 
 nRF Machine Learning (Edge Impulse)
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