ARM: zynq: remove incorrectly deleted file

My previous commit left the file empty and present in the
Makefile, which is a bit dirty and caused problems with
'make distclean', as pointed out by David Howells.
This hopefully cleans it up the right way.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: John Linn <john.linn@xilinx.com>