kconfig: add BOOT_SERIAL_DETECT pin for nrf52833DK

Add missing config for the nRF52833

Ref: NCSIDB-421

Signed-off-by: Håkon Øye Amundsen <haakon.amundsen@nordicsemi.no>
diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index aa4ee1f..dde97dd 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -518,7 +518,7 @@
 	int "Pin to trigger serial recovery mode"
 	default 6 if BOARD_NRF9160DK_NRF9160
 	default 11 if BOARD_NRF52840DK_NRF52840
-	default 13 if BOARD_NRF52DK_NRF52832
+	default 13 if BOARD_NRF52DK_NRF52832 || BOARD_NRF52833DK_NRF52833
 	default 23 if BOARD_NRF5340PDK_NRF5340_CPUAPP || BOARD_NRF5340PDK_NRF5340_CPUAPPNS || \
 		BOARD_NRF5340DK_NRF5340_CPUAPP || BOARD_NRF5340DK_NRF5340_CPUAPPNS
 	help