lib: fprotect: Delete Kconfig option FPROTECT_ENABLE_IS_PROTECTED

I can't see any reason for the Kconfig option
FPROTECT_ENABLE_IS_PROTECTED to exist so it is removed.

It is best-practice to rely on the linker to exclude unused functions
from the binary instead of using Kconfig options for every single
function.

This is a breaking change for anyone that is configuring
FPROTECT_ENABLE_IS_PROTECTED explicitly, but I don't expect anyone is
actually doing this.

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>

Author: SebastianBoe

include/fprotect.h

@@ -56,6 +56,8 @@ int fprotect_area_no_access(uint32_t start, size_t length);
 /**
  * @brief Check whether a block has already been protected.
  *
+ * NB: Only supported on HW platforms with ACL (CONFIG_HAS_HW_NRF_ACL).
+ *
  * @param[in]  addr  The address to check. The block containing this address
  *                   will be checked.
  *

lib/fprotect/Kconfig

@@ -59,13 +59,6 @@ config FPROTECT_ENABLE_NO_ACCESS
 	  Allows to protect flash pages both from reading and writing until the
 	  next reboot.
 
-config FPROTECT_ENABLE_IS_PROTECTED
-	bool
-	default y
-	depends on FPROTECT && HAS_HW_NRF_ACL
-	help
-	  Enable API to query if an address has been protected.
-
 config FPROTECT_APP
 	bool "Lock image partition using FPROTECT"
 	depends on PARTITION_MANAGER_ENABLED && FPROTECT

lib/fprotect/fprotect_acl.c

@@ -57,7 +57,6 @@ static int fprotect_set_permission(uint32_t start, size_t length,
 	return 0;
 }
 
-#ifdef CONFIG_FPROTECT_ENABLE_IS_PROTECTED
 uint32_t fprotect_is_protected(uint32_t addr)
 {
 	uint32_t region_idx;
@@ -90,7 +89,6 @@ uint32_t fprotect_is_protected(uint32_t addr)
 
 	return 0;
 }
-#endif
 
 int fprotect_area(uint32_t start, size_t length)
 {