Add missing git attributes

Change-Id: I0fd68ed33da702a02d183fc31edd1e0441b3e009
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/.gitattributes b/.gitattributes
index 22b7e0f..90b81a3 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -3,13 +3,13 @@
 # Text files that should be normalized
 *.c text
 *.h text
-*.py
-*.json
+*.py text
+*.json text
 *.txt text
-*.rst
-*.pdsc
-*.css
-*.svd
+*.rst text
+*.pdsc text
+*.css text
+*.svd text
 
 # Binary files that should not be normalized
 *.a binary