efi: define cache functions inside EFI_ENABLE ifdef

../src/shared/efi-loader.c:738:5: error: redefinition of 'efi_loader_get_config_timeout_one_shot'
 int efi_loader_get_config_timeout_one_shot(usec_t *ret) {
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../src/shared/efi-loader.c:9:
../src/shared/efi-loader.h:85:19: note: previous definition of 'efi_loader_get_config_timeout_one_shot' was here
 static inline int efi_loader_get_config_timeout_one_shot(usec_t *ret) {
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/shared/efi-loader.c:776:5: error: redefinition of 'efi_loader_update_entry_one_shot_cache'
 int efi_loader_update_entry_one_shot_cache(char **cache, struct stat *cache_stat) {
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../src/shared/efi-loader.c:9:
../src/shared/efi-loader.h:89:19: note: previous definition of 'efi_loader_update_entry_one_shot_cache' was here
 static inline int efi_loader_update_entry_one_shot_cache(char **cache, struct stat *cache_stat) {