Update .gitignore

Add *.pyc (to catch doc/DtsLexer.pyc) and *.patch (to catch patch files we
leave lying around).

Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

.gitignore

@@ -5,6 +5,8 @@
 *.gcno
 *.rej
 *.swp
+*.pyc
+*.patch
 .version
 skiboot-nosection.elf
 skiboot*.elf