fs: littlefs: Fix cache and lookahead size checks in littlefs_fs for …

…block devices

This fixes an issue where wrong values were checked against block device
defaults. Kconfig values are used when no filesystem config values are
provided, and the buffers are sized according to the Kconfig values,
but the checks were only performed against filesystem config variables.

subsys/fs/littlefs_fs.c

@@ -846,16 +846,16 @@ static int littlefs_init_cfg(struct fs_littlefs *fs, int flags)
 		lcp->read_size = block_size;
 		lcp->prog_size = block_size;
 
-		if (lcp->cache_size < new_cache_size) {
-			LOG_ERR("Configured cache size is too small: %d < %d", lcp->cache_size,
+		if (cache_size < new_cache_size) {
+			LOG_ERR("Configured cache size is too small: %d < %d", cache_size,
 				new_cache_size);
 			return -ENOMEM;
 		}
 		lcp->cache_size = new_cache_size;
 
-		if (lcp->lookahead_size < new_lookahead_size) {
+		if (lookahead_size < new_lookahead_size) {
 			LOG_ERR("Configured lookahead size is too small: %d < %d",
-				lcp->lookahead_size, new_lookahead_size);
+				lookahead_size, new_lookahead_size);
 			return -ENOMEM;
 		}
 		lcp->lookahead_size = new_lookahead_size;