endian: fix uint16_t specialization of le_to_cpu

Fortunately, we have not had cause to read any 16-bit fields out of
btrfs structures yet.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

include/crucible/endian.h

@@ -28,7 +28,7 @@ namespace crucible {
 	};
 
 	template<> struct le_to_cpu_helper<uint16_t> {
-		uint16_t operator()(const uint16_t v) { return le64toh(v); }
+		uint16_t operator()(const uint16_t v) { return le16toh(v); }
 	};
 
 	template<> struct le_to_cpu_helper<uint8_t> {