sysbuild: Kconfig: remove SUPPORT_SECURE_BOOT_BOOTCONF

symbol SB_SUPPORT_SECURE_BOOT_BOOTCONF_LOCK_WRITES isn't used
anymore.

Signed-off-by: Mateusz Michalek <mateusz.michalek@nordicsemi.no>

Author: michalek-no

sysbuild/Kconfig.mcuboot

@@ -148,11 +148,6 @@ choice BOOT_SIGNATURE_TYPE
 
 endchoice
 
-config MCUBOOT_FPROTECT_ALLOW_COMBINED_REGIONS
-	bool
-	default y
-	depends on SOC_SERIES_NRF54LX && !SECURE_BOOT_APPCORE
-
 config BOOT_SIGNATURE_TYPE_PURE
 	bool "Verify signature directly over image"
 	depends on SOC_SERIES_NRF54LX

sysbuild/Kconfig.secureboot

@@ -339,14 +339,10 @@ config SECURE_BOOT_PUBLIC_KEY_FILES
 	  empty string then only the public key hash corresponding to the private signing key used
 	  to sign the image is included in provision.hex.
 
-config SUPPORT_SECURE_BOOT_BOOTCONF_LOCK_WRITES
-	bool
-	depends on !MCUBOOT_FPROTECT_ALLOW_COMBINED_REGIONS
-	default y if SOC_NRF54L15_CPUAPP || SOC_NRF54L05_CPUAPP || SOC_NRF54L10_CPUAPP
-
 config SECURE_BOOT_BOOTCONF_LOCK_WRITES
 	bool "Protect bootloader's NVM from writes"
-	depends on SUPPORT_SECURE_BOOT_BOOTCONF_LOCK_WRITES
+	depends on SOC_NRF54L15_CPUAPP || SOC_NRF54L05_CPUAPP || SOC_NRF54L10_CPUAPP
+	default y
 	help
 	  Sets RRAMC's BOOTCONF region protection to disable writes.