boot: zephyr: Remove reference to deprecated BT_CTLR option

This Kconfig option has been deprecated. It has been replaced by
HAS_BT_CTLR, however that's a promptless option so it can't be explicitly
disabled.

Signed-off-by: Johan Hedberg <[email protected]>

Author: jhedberg

boot/zephyr/prj.conf

@@ -15,7 +15,6 @@ CONFIG_FLASH=y
 
 ### Various Zephyr boards enable features that we don't want.
 # CONFIG_BT is not set
-# CONFIG_BT_CTLR is not set
 # CONFIG_I2C is not set
 
 CONFIG_LOG=y