Revert "[nrf fromlist] boot: serial recovery: Add pca10090 default detect pin"

This reverts commit aebd4b9.

Signed-off-by: Andrzej Puzdrowski <[email protected]>

Author: nvlsianpu

boot/zephyr/Kconfig

@@ -258,7 +258,6 @@ config BOOT_SERIAL_DETECT_PORT
 
 config BOOT_SERIAL_DETECT_PIN
 	int "Pin to trigger serial recovery mode"
-	default 6 if BOARD_NRF9160_PCA10090
 	default 11 if BOARD_NRF52840_PCA10056
 	default 13 if BOARD_NRF52_PCA10040
 	help