Add Sony PlayStation support to Libreboot

I also added a "cleanargs" argument, similar to the makeargs
argument, to work around a build error.

This builds the PCSX-Redux PS1 BIOS. They reverse engineered
the Sony PS1 BIOS and wrote a free one under MIT license.

Run this:

./mk -b pcsx-redux

The file will appear: bin/playstation/openbios.bin

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/rom.sh

@@ -24,6 +24,13 @@ mkserprog()
 	[ "$XBMK_RELEASE" = "y" ] && mkrom_tarball "bin/serprog_$1"; return 0
 }
 
+copyps1bios()
+{
+	x_ rm -Rf bin/playstation
+	x_ mkdir -p bin/playstation
+	x_ cp src/pcsx-redux/src/mips/openbios/openbios.bin bin/playstation
+}
+
 mkpayload_grub()
 {
 	eval `setvars "" grub_modules grub_install_modules`