[PATCH v2] .gitattributes: use 'dts' diff driver for *.dtso files

Now we have the third extension for DT source files (overlay).
Give the diff=dts attribute to *.dtso as well.

While I was here, I merged *.c and *.o into *.[ch].

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v2:
  - Slightly shorten the code

 .gitattributes | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/.gitattributes b/.gitattributes
index 4b32eaa9571e..3471356b2387 100644
--- a/.gitattributes
+++ b/.gitattributes

@@ -1,4 +1,3 @@
-*.c   diff=cpp
-*.h   diff=cpp
-*.dtsi diff=dts
-*.dts  diff=dts
+*.[ch] diff=cpp
+*.dts diff=dts
+*.dts[io] diff=dts

-- 
2.34.1