gitignore: added kconfig names

Add the lines from the .gitignore found in bst-kconfig. As in the
previous commit, use bst-kconfig commit v2.6.34-4-g8168c0b

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>

.gitignore

@@ -13,3 +13,11 @@ tools/lm32-loader
 wrc_disasm.S
 wrc.ram
 wrc.vhd
+
+*.cmd
+*.o
+.tmp_*
+.config
+.config.old
+include/config
+include/generated
\ No newline at end of file