efi-loader: rename efi_stub_measured() → efi_measured_uki()

Let's say "uki" rather than "stub", since that is just too generic, and
we shouldn't limit us to our own stub anyway, but generally define a
concept of a "measured UKI", which is a UKI that measures its part to
PCR 11.

This is mostly preparation for exposing this check to the user via
ConditionSecurity=.

src/shared/efi-loader.c

@@ -238,7 +238,7 @@ int efi_stub_get_features(uint64_t *ret) {
         return 0;
 }
 
-int efi_stub_measured(int log_level) {
+int efi_measured_uki(int log_level) {
         _cleanup_free_ char *pcr_string = NULL;
         unsigned pcr_nr;
         int r;

src/shared/efi-loader.h

@@ -18,7 +18,7 @@ int efi_loader_get_entries(char ***ret);
 int efi_loader_get_features(uint64_t *ret);
 int efi_stub_get_features(uint64_t *ret);
 
-int efi_stub_measured(int log_level);
+int efi_measured_uki(int log_level);
 
 int efi_loader_get_config_timeout_one_shot(usec_t *ret);
 int efi_loader_update_entry_one_shot_cache(char **cache, struct stat *cache_stat);
@@ -45,7 +45,7 @@ static inline int efi_stub_get_features(uint64_t *ret) {
         return -EOPNOTSUPP;
 }
 
-static inline int efi_stub_measured(int log_level) {
+static inline int efi_measured_uki(int log_level) {
         return log_full_errno(log_level, SYNTHETIC_ERRNO(EOPNOTSUPP),
                               "Compiled without support for EFI");
 }