add mips to install options

Reference: /n/atom/patch/applied/usbinstallmips
Date: Tue May 20 19:27:43 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/lib/dist/amd64/install/main	Tue May 20 19:27:43 2014
+++ /sys/lib/dist/amd64/install/main	Tue May 20 19:27:43 2014
@@ -3,7 +3,7 @@
 
 fn init {
 	archlist = (386 68000 68020 alpha amd64 arm mips power power64 sparc sparc64)
-	archlist = (amd64 arm 386)
+	archlist = (amd64 arm 386 mips)
 	nl='
 '
 	yns=(yes no skip)