Add some basic .gitignore files

This still leaves driver and architecture-specific subdirectories alone,
but gets rid of the bulk of the "generic" generated files that we should
ignore.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/usr/.gitignore b/usr/.gitignore
new file mode 100644
index 0000000..be186a8
--- /dev/null
+++ b/usr/.gitignore
@@ -0,0 +1,7 @@
+#
+# Generated files
+#
+gen_init_cpio
+initramfs_data.cpio
+initramfs_data.cpio.gz
+initramfs_list