env: sf: update the use of macro ENV_SAVE_PTR

Remove CONFIG_IS_ENABLED(SAVEENV) as it is already tested in
the ENV_SAVE_PTR macro.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

env/sf.c

@@ -414,6 +414,6 @@ U_BOOT_ENV_LOCATION(sf) = {
 	.location	= ENVL_SPI_FLASH,
 	ENV_NAME("SPIFlash")
 	.load		= env_sf_load,
-	.save		= CONFIG_IS_ENABLED(SAVEENV) ? ENV_SAVE_PTR(env_sf_save) : NULL,
+	.save		= ENV_SAVE_PTR(env_sf_save),
 	.init		= env_sf_init,
 };